mRNA expression of slow type skeletal muscle/β-cardiac, type IIa and type IIx MHCs in human muscle fibers, myotubes and myoblasts. The mRNA quantity of MHC I, MHC IIa, and MHC IIx differs markedly between human muscle fibers, myotubes and myoblasts. (A) mRNA quantities of MHC I, MHC IIa, and MHC IIx in human muscle fibers, myotubes, and myoblasts. Data are arbitrary units where the values have been adjusted so that the mRNA quantities of the different MHC isoforms are approximately equal in muscle fibers so to better visualize the differences within each MHC isoform between the different cell types. Data are presented as the mean ± SEM. Aterisk denotes P < 0.05 relative to myoblasts, and number sign denotes P < 0.05 relative to myotubes. (B) mRNA quantities of the different MHC isoforms in human muscle fibers and myotubes. Data are presented as the mean ± SEM. Aterisk denotes P < 0.05 relative to MHC IIx, and number sign denotes P < 0.05 relative to MHC IIa
