Figure 4. Dot-blot analysis of BMP2/4 protein in OFE. Lane 1, 50 µg of OFE; lane 2, 500 ng of rhBMP-2 (Genzyme-Techne, USA; positive control); and lane 3, 50 µg of BSA (Sigma, St. Louis, MO, USA; negative control). Each sample was diluted as shown in left margin.