To validate the increased number of FAPs in DMD skeletal muscles, we quantified the number of PDGFRα-positive cells on transverse sections of muscle sampled from R-DMDdel52 and WT rats at the age of 12 months, and confirmed in situ the dramatic increase in the number of PDGFRα + cells (Fig. 6e, f). Here, PDGFRA is linked to Duchenne muscular dystrophy.