REAGENTS or RESOURCES	SOURCE	IDENTIFIER
Antibodies
Atrogin1/Fbx32	Abcam	ab168372
BrdU	Cell Signaling	52925
Cleaved caspase 3	Cell Signaling	9661
Cytokeratin 19	Abcam	ab52625
Dystrophin	Abcam	ab15277
elF3-f	Abcam	ab64177
MHC	Abcam	ab71808
Myostatin	Abcam	ab71808
Myostatin	R&D Systems	AF788
MuRF1	Cell Signaling	4305
Myc tag	Cell Signaling	22765
Smad4	Santa Cruz	sc-7966
Smad2	Cell Signaling	5339
pSmad2	Cell Signaling	3108
Twist1	Santa Cruz	sc-81417
Pax7	Abcam	Ab92317
Chemicals, Peptides, and Recombinant Proteins
Activin A	R&D Systems	338-AC-050
bFGF	Sigma-Aldrich	F3685
Collagenase D	Sigma-Aldrich	11088858001
Collagenase type 1	Sigma-Aldrich	SCR103
Dispase II	Sigma-Aldrich	4942078001
D-luciferin	Perkin Elmer	122799
JQ1	Sigma-Aldrich	SML-1524
Myostatin	R&D Systems	788-GB-010
puromycin	Sigma-Aldrich	P9620
Tamoxifen	Sigma-Aldrich	T5648
Critical Commercial Assays
Activin A ELISA kit	R&D Systems	DAC00B
SURVEYOR Mutation Detection Kit	Integrated DNA Technologies	706025
Recombinant DNA
Adenovirus-CMV.Cre (Ad.Cre)	Baylor College	Ad5-CMV-Cre
Atrogin1-Luc	This study	N/A
Mstn-Luc	This study	N/A
MuRF1-Luc	This study	N/A
pBABE-puro-mTwist1	Addgene	1783
pGIPZ-sh.Activin	Dharmacon	EG16323
pGIPZ-sh.control	Dharmacon	RHS4346
LentiCISPRv2	Addgene	52961
pSpCas9(BB)-2A-Puro (PX459)	Addgene	62988
Experimental Models: Cell Lines
B16	ATCC	CRL-6322
Suit2	ATCC	CRL-1687
MiaPaca2	ATCC	CRL-1420
CT-26	ATCC	CRL-2638
KP2	This study	N/A
KP1	This study	N/A
LLC	ATCC	CRL-1642
Experimental Models: Organisms/Strains
CAG-CreERT2	Jackson Lab.	004682
CAG-Loxp-CAT-Loxp-Twist1	Jackson Lab.	018543
CAG-Loxp-Stop-Loxp-Luciferase	NCI	01XAC
Loxp-Stop-Loxp-KrasG12D	NCI	01XJ6
NOD/SCID	Jackson Lab.	001303
p16Ink4A-Luciferase	Dr. Sharpless	Burd et al., 2013
Pax7.Cre	Jackson Lab.	010530
Pax7.CreERT2	Jackson Lab.	012476
Pdx1.Cre	NCI	01XL5
Prrx1.Cre	Jackson Lab.	005584
MCK.Cre	Jackson Lab.	006475
Trp53.Loxp/Loxp	Jackson Lab.	008462
Twist1.Loxp/Loxp	Dr. Xu	Baylor College of Medicine