Fig. 5. The myotube-dependent regulation of FAP differentiation is altered in aging. Aged FAPs were cultured alone or with aged MPs (Aged co-cult) (A and B) or with Young MPs (Aged/Young co-cult) (C and D) for 10 days in differentiation medium. (A and C) Adipocytes derived from aged FAPs were visualized by phase-contrast microscopy (scale bar: 5 µm). (B and D) Expression of FABP4, COL1A1 and FN1 was measured by quantitative Q-PCR (n=4 aged donors and n=3 young donors). ** P<0.01; * P<0.05; ns= non-significant; p values close to significance are indicated.