Fig. 3.

SHH acts synergistically with IGF1 and IGF2. Purified GCPs were either not treated (control) or treated with SHH or SHH + IGF1 (n = 4 for each condition). GCPs were also treated with SHH or SHH + IGF2 (n = 5 for each condition). Cell proliferation is significantly higher when GCPs are treated with both SHH + IGF1 (p < 0.001) and SHH + IGF2 (p < 0.001) than when they are treated with SHH alone. The concentrations of growth factors were as follows: IGF1: 20 ng/ml; IGF2: 40 ng/ml; SHH was used at 400 or 600 ng/ml. Similar results were obtained with these 2 concentrations of SHH in all experiments.