ERBB3 and breast carcinoma: Western blot analysis demonstrated that 5-minute HRGβ1 stimulation promoted EGFR, erbB3, erbB2 and EGFR phosphorylation and activation of the downstream signalling components Akt and ERK1/2 in MCF-7, T47D and BT-474 breast cancer cells, as shown in Figure 1a.