Figure 4.

Proliferation of SIPS cells was serum-dependent and stimulated with PDGF-BB. SIPS cells were treated with FBS (at the indicated concentrations) or PDGF-BB (at 25 ng/ml. After 24-hour-incubation, cells were labeled with BrdU for 3 hours. Cells were then fixed, and incubated with peroxidase-conju-gated anti-BrdU antibody. Then the peroxidase substrate 3,3’, 5,5’-tetramethylbenzidine was added, and BrdU incorporation was quantitated by differences in absorbance at wavelength 370 minus 492 nm (“O.D.”). Data are shown as mean ± SD (n = 6). ^aP < 0.01 vs. serum-free medium only. O.D.: optical density.