As shown in Fig. 2A,B, silence of HER2 by shRNA dramatically attenuated the U0126‐ and AZD6244‐induced Akt phosphorylation in SkBr3 and MCF‐7/HER2 breast cancer cells, respectively, and EGFR shRNA showed slightly inhibitory effect on Akt activation in these cell lines; however, silence of HER3 did not show this inhibitory effect (Fig. 2B). Here, ERBB3 is linked to breast cancer.