RT-PCR confirmation of selected differences in the transcriptional expression of undifferentiated WT and Mst KO MDSCs, detected with DNA microarrays. RNAs obtained from triplicate cultures of proliferating MDSCs, consecutive to those used for DNA microarrays in Tables 1 and 2, were subjected to RT-PCR with specific primers spanning an intron for the number of PCR cycles stated in parenthesis, as follows: Actc1 (30), Acta1 (30), MyoD1 (33), Pax3 (28), and GAPDH (26). (A) Ethidium bromide-stained agarose gels; (B) densitometry of relative band intensities referred to housekeeping gene for the indicated numbers of PCR cycles. Controls without cDNA were blank. *P < 0.05; ***P < 0.001. RT-PCR, reverse transcription polymerase chain reaction; WT, wild type; Mst KO, myostatin knockout; MDSC, muscle-derived stem cell; DNA, deoxyribonucleic acid; RNA, ribonucleic acid; GAPDH, glyceraldehyde 3-phosphate dehydrogenase.