Fig. 3. Critical period for BMP2-induced osteogenesis. (A,B) Sensitivity of MMCs to BMP2 under myogenic differentiation conditions. MMCs were cultured in the absence (white bars) or presence (black bars) of BMP2 for various intervals up to 48 hours (A). Numbers on the left represent the period of exposure to BMP2. At the end of the 48-hour culture, the cells were stained for ALP activity (B); images were obtained by bright-field microscopy. The level of ALP activity in each culture is shown as +, +/– or – below the images. (C) Induction of myogenesis-specific proteins in MMCs under myogenic differentiation conditions. Cells were cultured in pmDM for the indicated times, after which total lysates (20 µg of protein) were subjected to immunoblot analysis with antibodies to MHC and to myogenin.
