XAF1 and Duchenne muscular dystrophy: FAPs from Group B (DMD stable patients) had a statically significant upregulated expression of the proapoptotic gene Xaf1, interferon induced genes such as Ifi44l or Mx2 or the profibrotic differentiation transcription factor Spry1 while, FAPs from Group C (DMD declining patients) had the highest expression of collagen genes (Col1a1, Col1a2, Col3a1) but also high expression of genes actively involved cell division (Ccdc80 or Ccdc102b), indicating that in the declining patients FAPs actively proliferate and express EXM components replacing the muscle fibers lost.