CD38 and Duchenne muscular dystrophy: Although we cannot exclude a role for CD38 in non‐muscle cells, our results on improved NAD+ levels were measured in subcellular compartments of isolated cardiomyocytes from mdx/CD38−/− mice, and on Ca2+ signaling, in isolated cardiomyocytes from mdx/CD38−/− mice; human DMD myotubes point to an important role of CD38 in muscle functioning.