HIP1 and breast carcinoma: SHON is an oestrogen-regulated gene and the pure ERα antagonist ICI 182,780 partially attenuates SHON-stimulated growth promotion in MCF-7 breast cancer cells, indicating that SHON signalling is at least, in part, mediated by ERα.7 However, ERα-regulated functions are thought to play a pivotal role in determining the response to anti-oestrogen therapy.