AKT1 and breast cancer: In SK-BR-3 breast cancer cells transiently stimulated with HER2-VIA, phosphorylation of HER2 on sites 877, 1,221, 1,222 and 1,248, as well as phosphorylation of the downstream HER2 signaling molecules Akt and ERK, was detected (Figure 3, lanes 1 to 5).