The effect of BMP-2 on the osteogenic expression in cell lines. Osteogenic gene expression was examined in MC3T3-E1 (dot-dash line), C2C12 (straight line) and NIH/3T3 (dotted line) cell lines using qPCR with the data normalized to the housekeeping gene Gapdh. Ap expression was measured as an early osteogenic marker in cells grown in the absence (A) or the presence (B) of BMP-2. Ocn gene expression was measured as a late osteogenic marker in cells cultured in the absence of BMP-2 (C) or with BMP-2 added (D). In addition, the dose- and cell-dependent effect of BMP-2 on AP activity after 6 days (E) and mineralized nodule formation after 12 days (F) was measured in all three cell lines. Scale bar = 100 μm.