Table 1. Candidate driver mutations in two immortalized MEF cell lines.

Cell line	Gene symbol	Function	Transcript ID	cDNA change	AA change	Mutated in human tumors (COSMIC, %)	Known to be involved in senescence
AA_2	Cbx7	PRC1 complex	NM_144811	c.T32A	p.F11Y	0.2
	Cdkn1aa	Cell cycle	NM_007669.5	c.94-2A>T	splice site	0.3	Yes
	Ep400a	TIP60 complex	NM_029337	c.A970T	p.R324X	2.2	Yes
	Ext1	Glycosaminoglycan metabolism	NM_010162	c.A103T	p.S35C	0.5
	Ext1a			c.A1036T	p.R346X
	Hrasa	MAPK signaling	NM_001130443	c.A182T	p.Q61L	2.7
	Jak2	JAK-STAT signaling	NM_001048177	c.A2479T	p.I827L	30.0
	Smarcc1a	BAF complex	NM_009211	c.A356T	p.H119L	0.7	Yes
	Smyd1	H3K4 methylation	NM_009762	c.T1072A	p.S358T	0.7
	Tp53a	Transcription, DNA repair	NM_000546.4	c.A391T	p.N131Y	26.8	Yes
	Tp53a			c.A871T	p.K291X
MNNG_4	Apca	Wnt signaling	NM_007462	c.C8278T	p.P2760S	10.9	Yes
	Atma	DNA repair	NM_007499	c.C3092T	p.T1031I	4.2	Yes
	Baz1aa	ACF complex	NM_013815	c.G392A	p.R131K	0.8
	Brca1	DNA repair	NM_009764	c.C4322T	p.P1441L	1.3	Yes
	Gatad2a	Histone deacetylation	NM_001113345	c.G243A	p.M81I	0.3
	Jak1a	JAK-STAT signaling	NM_146145	c.C1327T	p.P443S	1.0
	Jak1a			c.C1286T	p.P429L
	Kmt2aa	H3K4 methylation	NM_001081049	c.C9755T	p.P3252L	1.6
	Prdm1	Transcription	NM_007548	c.C2420T	p.P807L	1.1
	Setd1aa	H3K4 methylation	NM_178029	c.G1499A	p.S500N	1.2
	Setd1aa			c.G5095A	p.D1699N
	Sin3ba	HDAC	NM_009188	c.C2441T	p.T814I	0.7	Yes
	Smarcd2a	BAF complex	NM_031878	c.G497A	p.G166E	0.3
	Trrapa	TIP60 complex	NM_001081362	c.G6952A	p.V2318M	2.6
	Tp53a	Transcription, DNA repair	NM_000546.4	c.C454T	p.P152S	26.8	Yes
	Tp53a			c.C476T	p.A159V

^aValidated by Sanger sequencing (Supplementary Figures S2 and S3).