For osteogenic differentiation, C3HT101/2 (ATCC) cells were incubated in 48-well tissue culture plates at 1.25 × 104 cells/cm2 . After 24-h incubation, the culture media were changed to fresh media containing 300 ng/ml BMP-2 (Sigma, St. Louis, Missouri, United States). Total cellular RNA was prepared as described above, and osteocalcin, β-actin, and GAPDH gene expression at indicated times after BMP-2 treatment was quantified by RT-PCR.