CDKN2A and Duchenne muscular dystrophy: Western blot analysis showed the expression of p16 protein in p16+/+ XDmdY rats (DMD rats) while no band was detectable in p16+/+ XY rats (WT rats), which is consistent with the result of the elevated levels of CDKN2A mRNA expression in DMD rats in Fig. 2a,b (Supplementary Figure 4c).