We now report that in breast cancer cells where ErbB2 is overexpressed, βGBP was unable to affect cell proliferation, but, while unable to quench redundant mitogenic signalling and inhibit cell proliferation, by downregulating PI3K activity and suppressing akt gene expression, βGBP had strong therapeutic efficacy that resulted in massive apoptotic death. Here, ERBB2 is linked to breast carcinoma.