Paul G. Allen Family, and Vallee Foundations; and J. and P. Poitras,R. Metcalfe, and D. Cheng. A.R. is on the scientific advisoryboard for Syros Pharmaceuticals and Thermo Fisher and is aconsultant for Driver Group. N.E.S., J.W., O.S., and F.Z. are listedas inventors on a related patent application. Plasmids are availablefrom Addgene, subject to a material transfer agreement. Deepsequencing data are available at Sequence Read Archive under

BioProject accession number PRJNA324504, and software toolsare available on GitHub (https://github.com/nsanjana/BashRegion).

SUPPLEMENTARY MATERIALS

www.sciencemag.org/content/353/6307/1545/suppl/DC1Materials and Methods

Supplementary TextFigs. S1 to S13Tables S1 to S7References (26–42)

25 March 2016; accepted 16 August 201610.1126/science.aaf7613

GENE REGULATION

Cyclin A2 is an RNA binding proteinthat controls Mre11mRNA translationArun Kanakkanthara,1 Karthik B. Jeganathan,1 Jazeel F. Limzerwala,2 Darren J. Baker,1

Masakazu Hamada,1 Hyun-Ja Nam,1 Willemijn H. van Deursen,1 Naomi Hamada,1

Ryan M. Naylor,2 Nicole A. Becker,2 Brian A. Davies,2 Janine H. van Ree,1 Georges Mer,2

Virginia S. Shapiro,3 L. James Maher III,2 David J. Katzmann,2 Jan M. van Deursen1,2*

Cyclin A2 activates the cyclin-dependent kinases Cdk1 and Cdk2 and is expressed at elevatedlevels from S phase until early mitosis.We found that mutant mice that cannot elevate cyclinA2 are chromosomally unstable and tumor-prone. Underlying the chromosomal instabilityis a failure to up-regulate themeiotic recombination 11 (Mre11) nuclease in S phase,which leadsto impaired resolution of stalled replication forks, insufficient repair of double-stranded DNAbreaks, and improper segregation of sister chromosomes. Unexpectedly, cyclin A2 controlledMre11 abundance through a C-terminal RNA binding domain that selectively and directly bindsMre11 transcripts to mediate polysome loading and translation.These data reveal cyclin A2 as amechanistically diverse regulator of DNA replication combining multifaceted kinase-dependentfunctions with a kinase-independent, RNA binding–dependent role that ensures adequate repairof common replication errors.

Cyclin A2 is a core cell cycle regulator thatactivates Cdk1 and Cdk2. Cyclin A2 levelsincrease upon S phase entry and remainhigh until its proteasome-dependent de-struction in prometaphase (1). Cyclin A2–

Cdk complexes that assemble at the onset ofS phase drive chromosome duplication throughphosphorylation of key DNA replication factors.Subsequently, cyclin A2–Cdk activity initiatesmitosis by phosphorylating and inactivating theprotein kinase Wee1, resulting in activation andnuclear localization of cyclin B1–Cdk1. Duringearly mitosis, cyclin A2 is implicated in mitoticspindle anchoring (2) and correction of aberrantkinetochore-microtubule attachments (3). Further-more, in a Cdk-independent manner, cyclin A2regulates RhoA and RhoC, two guanosine tri-phosphatases implicated in cell morphogenesis,adhesion, and migration (4).Inmice, cyclin A2 is essential for early embryo-

genesis, limiting investigations of its biologicalfunctions (5). Studies of conditional knockoutmice revealed that cyclin A2 is essential for cellcycle progression of certain cell types, includingpluripotent and hematopoietic stem cells andselect neuronal progenitors, yet is dispensablein fibroblasts because of redundancywith cyclin

E in this cell type (6). To uncover novel biologi-cal processes that critically depend on a full com-plement of cyclin A2, we used a combination ofknockout (Ccna2–) and hypomorphic (Ccna2H)alleles tomarkedly down-regulate cyclinA2 expres-sion in mice without overtly affecting embryogen-esis or postnatal development. Ccna2Hwas createdby targeted insertion of a neomycin resistancecassette intoCcna2 intron 2;Ccna2–was createdbygene trap mutagenesis (fig. S1, A to D). Ccna2–/H

mice showed markedly reduced levels of cyclinA2 protein in tissues with a high mitotic index, in-cluding small intestine, bonemarrow, and spleen(Fig. 1A). In contrast, cyclin A2 levels appearednormal in tissues with few cycling cells, such asbrain, liver, and lung. However, actively cyclingcultured lung epithelial cells from Ccna2–/H micehad lower amounts of cyclin A2 relative to thewild type (Fig. 1A). Analysis of mouse embryonicfibroblasts (MEFs) confirmed this, with Ccna2–/H

MEFs expressing only ~25% of normal cyclin A2levels (Fig. 1A and fig. S1E). In Ccna2+/+ MEFs,cyclin A2 expression typically started to increaseduringG1 and peaked fromG2 until prophase (fig.S2). Cyclin A2 levels remained low in Ccna2–/H

MEFs throughout the cell cycle, resulting inmarkedly reduced Cdk activity during S and G2

phase (fig. S3). Despite these abnormalities,Ccna2–/H MEFs showed a normal cell cycle pro-file (fig. S4).Both cyclin A2 deficiency and overabundance

have been observed in human tumors and predictpoor clinical outcome (7), but whether and how

cyclin A2 deregulation drives malignant growthis unknown. To determinewhether reduced cyclinA2 expression contributes to tumorigenesis, wetreated Ccna2+/+ and Ccna2–/H mice with 7,12-dimethylbenz(a)anthracene (DMBA), a carcino-gen that predisposesmice to lung adenomas andskin papillomas (8). Ccna2–/H mice showed amarked increase in tumor incidence and multi-plicity in both lung and skin (Fig. 1B). Further-more, lung adenomas of Ccna2–/H mice werelarger in size. Ccna2–/H mice were also moresusceptible to spontaneous tumors, particularlylung adenomas (Fig. 1C). Collectively, these dataestablish that cyclin A2 insufficiency promotesneoplastic transformation.To identify the underlying defects, we screened

for chromosomal instability, a hallmark of hu-man malignancies. Splenocytes and MEFs ofCcna2–/H mice had increased aneuploidy (fig.S5A). Ccna2–/H MEFs showed predisposition totwo types of chromosome segregation errors: chro-matin bridges and lagging chromosomes (Fig. 2A).The latter are the result of merotelic attachment,amicrotubule-kinetochoremalattachment causedby spindle defects, including defects in attachmenterror correction, microtubule dynamics, mitotictiming, centrosome disjunction, and centrosomemovement (9).We systematically screenedCcna2–/H

MEFs for lagging chromosomes, and by measur-ing the separation between centrosomes in G2

and prophase, we found that the movement ofsister centrosomes to opposite poleswas impaired(Fig. 2B and fig. S5, B to F). Cells with delayedcentrosomeseparation formasymmetrical spindlesand lagging chromosomes at increased rates (10).Consistent with this, spindle geometry defects oc-curred at high frequency in Ccna2–/H MEFs (Fig.2C). Furthermore, lagging chromosomes weremore prevalent in Ccna2–/H MEFs with asym-metrical as opposed to symmetrical spindles (fig.S5, G and H).The motor protein Eg5 accumulates at centro-

somes in prophase to drive centrosomemovement(11). Loading of Eg5 was markedly reduced inCcna2–/H MEFs, as was centrosomal accumula-tion of cyclin A2 (Fig. 2D and fig. S5I). Centrosometargeting of Eg5 is dependent on Cdk-mediatedphosphorylation of Thr926 (T926) (11). T926 phos-phorylation was reduced in Ccna2–/H MEFs de-spite normal expression of Eg5 and alternativeCdk1 and Cdk2 partners, including cyclins B andE (Fig. 2E and fig. S5J). Restoration of cyclin A2expression in Ccna2–/H MEFs normalized T926phosphorylation and corrected centrosomal load-ing of Eg5, centrosome movement, and spindlegeometry (fig. S5, K to N). Collectively, theseresults uncover a nonredundant catalytic roleof cyclin A2–Cdk in targeting Eg5 to centrosomal

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1Department of Pediatric and Adolescent Medicine, MayoClinic, Rochester, MN, USA. 2Department of Biochemistryand Molecular Biology, Mayo Clinic, Rochester, MN, USA.3Department of Immunology, Mayo Clinic, Rochester, MN, USA.*Corresponding author. Email: vandeursen.jan@mayo.edu

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microtubules for proper centrosome movementand spindle formation.Chromatin bridges, the other chromosome

segregation defect observed in Ccna2–/H MEFs,can be caused by defects in DNA replication,DNA decatenation, or cohesin cleavage (12, 13).Ccna2–/H MEFs properly targeted topoisomeraseIIa to inner centromeric regions early in mitosisand had normal separase activity (fig. S6, A andB), which suggests that bridge formation wasunlikely to result from decatenation or cohesincleavage defects. In DNA fiber assays, replicationforks of Ccna2–/H cells progressed at reduced ratesand stalled more frequently than did Ccna2+/+

cells (Fig. 3A and fig. S6, C to G). Phosphorylationof checkpoint kinase 1 (Chk1) at Ser345 (S345), amarker of replication stress (14), was elevatedin Ccna2–/H MEFs (Fig. 3B). Furthermore, the effi-ciency with which hydroxyurea-stalled replicationforks of Ccna2–/H MEFs restarted was markedly

reduced (fig. S6H). Unreplicated single-strandedDNA (ssDNA) at stalled replication forks is vul-nerable to breakage (14). Visualization of DNAdamage repair foci by staining for the presenceof the DNA repair proteins gH2AX and 53BP1demonstrated thatCcna2–/H cells accumulatemoredouble-stranded DNA breaks (DSBs; fig. S7, A toF). Furthermore, radiation-induced DSBs wererepaired with reduced efficiency in Ccna2–/H

MEFs (fig. S7, G and H). Rad51, a key compo-nent of DSB repair (15), failed to accumulate atradiation-induced DSBs in a large proportion ofCcna2–/H MEFs (fig. S7, I to L). Rad51 accumu-lation at DSBs is dependent on end resection, akey step in the repair process that ismeasured bystaining for RPA2, a repair protein that stabilizesssDNA intermediates (15). Analysis of RPA2 andgH2AX at 8 hours after g-irradiation revealedthat RPA2 localization at DSBs was markedlyreduced in Ccna2–/H MEFs (fig. S7, M and N).

TheMRNcomplex, composed ofMre11, Rad50,and Nbs1, plays a central role in both replicationfork restart and DSB repair (15). Western blotanalysis revealed that levels of Mre11 and Rad50protein, but not Nbs1 protein, were consistentlyreduced in both irradiated and nonirradiatedCcna2–/H MEFs (Fig. 3C). Levels of Mre11 andRad50 were also low in Ccna2–/H tumors, al-though Cdk2 activity appeared normal (fig. S8).Analysis of cell cycle–dependent expression showedthat both Mre11 and Rad50 levels peaked inCcna2+/+ MEFs during S and G2 phase, similarto cyclin A2 expression (figs. S9 and S10). Ex-pression ofMre11 and Rad50 in S and G2 phaseswas substantially lower in Ccna2–/H MEFs. Ec-topic expression of cyclin A2 restored bothMre11and Rad50 protein levels (Fig. 3D). Mre11 andRad50 mRNA levels and ratios of nuclear tocytoplasmic distribution in Ccna2–/H MEFs weresimilar to those of Ccna2+/+ MEFs (fig. S11, A toC), indicating that reduced expression of Mre11and Rad50 was not due to altered transcriptionor defective nuclear export. Furthermore, pro-teasome degradation was not responsible, astreatment of Ccna2–/HMEFswith the proteasomeinhibitor MG132 did not alter Mre11 and Rad50levels (fig. S11D).However,Mre11 and Rad50mRNA abundance

in polysomes was reduced in Ccna2–/H MEFs,suggesting reduced translation (Fig. 3E and fig.S12, A to C). To determine whether this was adirect effect, we immunoprecipitated cyclin A2and analyzed it for the presence ofMre11, Rad50transcripts, and several control transcripts byquantitative reverse transcription polymerasechain reaction (RT-qPCR). Intriguingly, cyclinA2 selectively precipitated Mre11 transcripts inCcna2+/+ MEFs (Fig. 3F). Similar results wereobtained using human primary fibroblasts andHeLa cells (fig. S12D). Cyclin A2 knockdown inthese cells resulted in reducedMRE11 andRAD50protein levels, consistent with results in Ccna2–/H

MEFs (fig. S12E). Cyclin A1 had no Mre11 RNAbinding ability (fig. S12, F and G). Two obser-vations suggested that cyclin A2 regulation ofMre11 and Rad50 was Cdk-independent: NeitherCdk2 nor Cdk1 immunoprecipitation enrichedMre11 transcripts comparably to cyclin A2 im-munoprecipitation (fig. S12H), and inhibition ofCdk2 activity in wild-type MEFs by roscovitinehad no impact on Mre11 levels (fig. S12I). Mre11knockdown resulted in low Rad50 protein levels,but Rad50 depletion did not affect Mre11, indi-cating that Rad50 abundance isMre11-dependent(fig. S13, A and B). Ectopic expression of Mre11in Ccna2–/H MEFs normalized both Mre11 andRad50 protein levels but had no impact on cyclinA2 levels (Fig. 3G). Coincidentally, polysome asso-ciation of Rad50 mRNA was restored (fig. S13C),reinforcing the idea that Rad50 translation isMre11-dependent, although Mre11 immunopre-cipitates did not contain Rad50 transcripts (fig.S13D). Ectopic expression of Mre11 in Ccna2–/H

cells rescued DSBs and chromatin bridges, indi-cating thatMre11 deficiency is the driver of thesechromosomal phenotypes (fig. S13, E and F).Expression of CtIP, a binding partner of theMRN

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Fig. 1. Cyclin A2 insufficiency drives tumorigenesis. (A) Immunoblot analysis of cyclin A2 in tissuesand cultured primary cells of Ccna2+/+ (+/+) and Ccna2–/H (–/H) mice. Actin was used as a loadingcontrol. (B) Incidence, multiplicity, and size of DMBA-induced tumors in 5-month-old mice. (C) Overalland tissue-specific incidences of spontaneous tumors in 16-month-old mice. HCA, hepatocellular adenomas.**P < 0.01, ***P < 0.001.

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Fig. 2. Cyclin A2–Cdk1 regulates spindle polemovement by targeting Eg5 to centrosomes.(A) Live-cell imaging analysis of chromosome mis-segregations inMEFs expressing histoneH2B taggedwith a monomeric form of red fluorescent protein(H2B-mRFP). Inset shows examples of Ccna2–/H

MEFswith chromosome laggingor bridging. (B) Left:Images ofMEFs in prophase stained for g-tubulin andDNA. Right: Incidence of prophases with delayedcentrosomemovement. (C) Left:Maximum-intensityprojection images of immunostainedmetaphases.Right: Incidence of cells with abnormal spindle geom-etry. (D) Left: Images of prophase MEFs immuno-stained for Eg5 and g-tubulin. Right: Quantificationof Eg5 signal at centrosomes in prophase. (E) Immu-noblot analysis of phosphorylated Eg5T926 and totalEg5 in asynchronouslyculturedMEFs. Actinwas usedas loading control. DNA in (B) to (D) was visualizedwith Hoechst. Scale bars, 10 mm. Data are means ±SEM [N = 6 independent MEF lines per genotype in(A), and N = 3 in (B) to (D); 10 cells per line wereanalyzed in (B) to (D)]. *P < 0.05, **P < 0.01, ***P <0.001 (unpaired t test).

Fig. 3. Cyclin A2 interacts with Mre11 mRNA to regulate its translation.(A) Percentages and examples of ongoingand stalled replication forks inMEFs.Inset shows examples of fibers. (B) Immunoblot analysis for Chk1 phospho-rylation at S345. (C) Immunoblots of control and g-irradiated (IR) MEF lysatesprobed for the indicated proteins. (D) Immunoblot analysis of asynchronouslyculturedMEFs transduced with control (TSIN) orCcna2-containing (cycA2-TSIN)lentiviruses. (E) Quantification of Mre11mRNA in polysome fractions of MEFs.

(F) Cyclin A2 RNA immunoprecipitation (IP) in MEFs followed by RT-qPCRanalysis for the indicated genes. IgG, immunoglobulin G; WB,Western blot.(G) As (D) but using control (TSIN) and Mre11-containing lentivirus. (H) Lu-ciferase activity in cells transfected with 3′UTR of Mre11 mRNA. UT, un-transfected; EV, empty vector. Actin was used as loading control in (B), (C), (D),and (G). Data in (A), (E), (F), and (H) aremeans ±SEM (N=3 independentMEFlines per genotype). *P < 0.05, **P < 0.01 (unpaired t test).

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complex implicated in end resection, was sub-normal in Ccna2–/H MEFs through a Cdk2-dependent, Mre11-independent mechanism andtherefore is unlikely to contribute to the chro-mosomal phenotype of Ccna2–/H cells (fig. S14).RNA sequencing analysis of cyclin A2, E2, and

B1 immunoprecipitates demonstrated that cyclinA2 exclusively binds Mre11 transcripts and thatcyclins E2 and B1 have no RNA binding ability(tables S1 to S3). Mre11 RNA sequence readsexclusively mapped to the 3′ untranslated region(3′UTR), indicating that this region contains thecyclin A2 binding site (fig. S15A). When intro-duced downstream of a luciferase reporter, theMre11 3′UTR enhanced luciferase activity inCcna2+/+MEFsbutnot inCcna2–/HMEFs (Fig. 3H).Ectopic expression of cyclin A2 inCcna2–/HMEFscorrected this deficiency (fig. S15B).Expression of hemagglutinin (HA)–tagged

cyclin A2 deletion mutants in MEFs revealedthat residues 302 to 432 are necessary and suf-ficient for Mre11 transcript binding (Fig. 4A).This fragment, which lacks Cdk-binding ability,restored Mre11 and Rad50 expression and pre-vented DSB formation in Ccna2–/H MEFs (Fig.4B and fig. S16A) but did not correct Cdk-dependent phenotypes such as Eg5 loading,

centrosomemovement, spindle geometry, andchromosome lagging (fig. S16, B to F). Conversely,expression of amino acids 1 to 301, a fragmentthat binds to Cdk, corrected the latter defects butfailed to restore Mre11 and Rad50 expression andDSB repair (fig. S16, G to K). Using deletionmuta-genesis, we identified two subregions within theMre11 3′UTR, a 150-nucleotide (nt) segment at the5′ end and a 34-nt segment at the 3′ end, as poten-tial cyclin A2 binding sites (Fig. 4C). Recombinantglutathione S-transferase (GST)–cyclin A2302-432

directly bound a radiolabeledRNAprobe spanningthe last 32 nt of theMre11 3′UTR in an electro-phoreticmobility shift assay, but not a scrambled32-nt oligomer (32-mer) (Fig. 4D and fig. S17, AandB). NeitherGST–cyclinA21-209 norGST–cyclinA2302-432(4M), which carries mutations in four puta-tive ribonucleic acid contact sites required for resto-ration of Mre11 and Rad50 expression in Ccna2–/H

MEFsby ectopic expression of cyclinA2 (fig. S17, B toE), was able to bind theMre11 RNA probe (Fig. 4D).Translation initiation factor eIF4A2, a previ-

ously documented putative cyclin A2 interactor(16), supershifted GST–cyclin A2302-432–boundMre11 RNA complexes but did not bind the probein the absence of cyclin A2 (Fig. 4E). eIF4A2, butnot Cdk1 or Cdk2, coimmunoprecipitated cyclin

A2 under physiological conditions, indicatingthat cyclin A2 bound to Mre11 mRNA is free ofCdk binding partners (Fig. 4F). Cyclin A2 inter-acted with eIF4A2 and Mre11 RNA through acommon domain (fig. S17F). Finally, using theCRISPR/Cas9 technique, we generated micehomozygously lacking the last 47 nt of theMre11 3′UTR (designated Mre11DA2/DA2 MEFs),which were viable and overtly normal (fig.S18). Mre11DA2/DA2 MEFs had normal amounts ofMre11 mRNA, but the transcripts showed mark-edly reduced polysome association, resulting in lowMre11 protein levels (fig. S19, A to D).Mre11DA2/DA2

MEFs entirely phenocopied Ccna2–/H MEFs, ex-cept for phenotypes related to phosphorylationof Eg5 mediated by cyclin A2–Cdk (fig. S19, E toK, and fig. S20).Our work exposed two novel cyclin A2 func-

tions. First, we identified a role for the cyclin A2N terminus in the formation of bipolar mitoticspindles by regulating Eg5 loading onto centro-somes through phosphorylation of T926. Second,the C terminus of cyclin A2, which has low se-quence conservation among cyclin family mem-bers, directly binds to a conserved region in the3′UTRofMre11 transcripts to promote their trans-lation, presumably through an interaction witheIF4A2. In doing so, cyclin A2 coordinates itswell-established Cdk-dependent functions in theinitiation and progression of DNA synthesis (16)while simultaneously reinforcing stabilization ofthe keymachinery responsible for repairing DNAlesions caused by replication errors. Cyclins havehitherto not been implicated inRNAbinding. Theobservation that cyclin A2 seemingly interactswith just a single transcript,Mre11 mRNA, wasunexpected and appears to be a unique featureamong RNA binding proteins.

REFERENCES AND NOTES

1. H. Hochegger, S. Takeda, T. Hunt, Nat. Rev. Mol. Cell Biol. 9,910–916 (2008).

2. H. Beamish et al., J. Biol. Chem. 284, 29015–29023 (2009).3. L. Kabeche, D. A. Compton, Nature 502, 110–113 (2013).4. N. Arsic et al., J. Cell Biol. 196, 147–162 (2012).5. M. Murphy et al., Nat. Genet. 15, 83–86 (1997).6. I. Kalaszczynska et al., Cell 138, 352–365 (2009).7. C. H. Yam, T. K. Fung,R. Y. Poon,Cell.Mol. Life Sci.59, 1317–1326 (2002).8. M. Serrano et al., Cell 85, 27–37 (1996).9. R. M. Naylor, K. B. Jeganathan, X. Cao, J. M. van Deursen,

J. Clin. Invest. 126, 543–559 (2016).10. J. H. van Ree, H. J. Nam, K. B. Jeganathan, A. Kanakkanthara,

J. M. van Deursen, Nat. Cell Biol. 18, 814–821 (2016).11. A. Slangy et al., Cell 83, 1159–1169 (1995).12. H. J. Nam, J. M. van Deursen, Nat. Cell Biol. 16, 538–549 (2014).13. R. A. Burrell et al., Nature 494, 492–496 (2013).14. M. K. Zeman, K. A. Cimprich, Nat. Cell Biol. 16, 2–9 (2014).15. T. H. Stracker, J. H. Petrini,Nat. Rev. Mol. Cell Biol. 12, 90–103 (2011).16. F. W. Pagliuca et al., Mol. Cell 43, 406–417 (2011).

ACKNOWLEDGMENTS

We thank W. Zhou, M. Li, F. Jin, and X. Wang for assistance andD. Compton for providing photoactivatable GFP-tagged a-tubulin.Supported by NIH grants CA126828 and CA168709 (J.M.v.D.)and CA166025 (L.J.M.).

SUPPLEMENTARY MATERIALS

www.sciencemag.org/content/353/6307/1549/suppl/DC1Materials and MethodsFigs. S1 to S20Tables S1 to S4References (17–38)

24 March 2016; accepted 29 August 201610.1126/science.aaf7463

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Fig. 4. The cyclin A2 C terminus directly binds to a conserved sequence in the Mre11 3′UTR.(A) RNA immunoprecipitation in wild-type MEFs expressing the indicated HA-tagged cyclin A2 deletionmutants. RNAs coprecipitating with HA–cyclin A2 mutants were analyzed by RT-qPCR. (B) Quantificationof cyclin A2302-432–expressing cells with two or more gH2AX- and 53BP1-colocalized foci. (C) Luciferaseactivity in MEFs transfected with different regions of the Mre11 3′UTR. (D) Representative native gel shiftsshowing a specific interaction between recombinant cyclin A2302-432 and the Mre11 3′UTR conservedsequence. (E) Same as (D) but in the presence of recombinant human eIF4A2. (F) Western blot analysis ofeIF4A2-coprecipitating proteins in wild-type MEFs. Data in (A) to (C) are means ± SEM (N = 3 independentMEF lines per genotype). *P < 0.05, **P < 0.01, ***P < 0.001 (unpaired t test).

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mRNA translationMre11Cyclin A2 is an RNA binding protein that controls

Mer, Virginia S. Shapiro, L. James Maher III, David J. Katzmann and Jan M. van DeursenWillemijn H. van Deursen, Naomi Hamada, Ryan M. Naylor, Nicole A. Becker, Brian A. Davies, Janine H. van Ree, Georges Arun Kanakkanthara, Karthik B. Jeganathan, Jazeel F. Limzerwala, Darren J. Baker, Masakazu Hamada, Hyun-Ja Nam,

DOI: 10.1126/science.aaf7463 (6307), 1549-1552.353Science 

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MATERIALSSUPPLEMENTARY http://science.sciencemag.org/content/suppl/2016/09/28/353.6307.1549.DC1

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