Figure 1.

Dose responses of cell proliferation and the ErbB4 and p80 amounts to NRG1. A: Cells were deprived of serum for 8 h and treated for 24 h without (0) or with the indicated doses of NRG1, followed by cell proliferation assay. Data are presented as mean ± S.E. (fold of control) of relative values normalized to the mean value of control cells cultured without NRG1, obtained from three independent experiments. a and b, p < 0.05 vs control cells and cells treated with 50 ng/ml NRG1, respectively. B: The same cells used for cell proliferation assay were analyzed by Western blotting for endogenous ErbB4, p80, and β-actin as the loading control.