ERBB3 and breast cancer: To confirm these, co-immunoprecipitation and immunoblotting were performed and the results showed that phosphorylation of HER1, 2 and 3, binding of HER3 to PI3K p85, as well as downstream Akt activity were dramatically suppressed by MP470 plus Erlotinib in LNCaP (Fig. 6A) and T47D breast cancer cells (Fig. 6B).