Fig. 6. Interaction of SDF1 with other extracellular factors controlling myogenesis. C2C12 cells were treated at the switch from growth to differentiation conditions with either SDF1 (10 ng/ml), FGF2 (10 ng/ml) or IGF1 (10 ng/ml) alone or in combination as indicated. After 48 hours, myogenin protein levels were analyzed by western blotting. Immunoreactive protein bands were measured by densitometry and corrected for β-actin. Data represent average myogenin protein levels ± s.d. as determined in four independent experiments. SDF1 did not further modify the known inhibitory influences of FGF2 on myogenic differentiation. By apparent contrast, SDF1 completely prevented the established stimulatory influences of IGF1 on myogenesis. C, control; ^aP<0.05, IGF1 vs control; ^bP<0.05, IGF1+SDF1 vs IGF1.