Fig. 1. Dose-response effects of BMP-7 on muscle satellite cell differentiation. Primary muscle satellite cells derived from either wild-type (WT) or MyoD^-/- mice were treated for 3 days with 0, 100 or 400 ng/ml of BMP-7. Upper panel, cultures stained for MHC (brown) or ALP activity (blue). Lower panel, the percentage area of MHC-positive cells was measured using NIH image software (n=6). Cell lysates from parallel cultures were assayed for total ALP activity using p-nitrophenylphosphate as a substrate. The ALP activity is expressed as OD_{405 nm}/min/mg protein±s.d. (n=3). Scale bar, 250 µm.