ZMPSTE24 and progeroid syndrome: To further understand the role of Cdon in muscle aging, we examined expression of Cdon and Itgb1* in satellite cells from mice with the Zmpste24 protease deficiency, of a model for progeria.39 These mice exhibit, among other aging‐related phenotypes, premature muscle loss associated with elevated cellular senescence and reduced proliferation of muscle stem cells.40, 41, 42 Myofibers isolated from EDL muscles of 4‐month‐old wild type or Zmpste24−/− mice were immunostained for Cdon, Itgb1*, and Pax7 (Figure6E–6G).