ERBB2 and breast cancer: The overexpression of Hsp27 in AS-B145 or BT-474 breast cancer cells diminished the inhibitory effect of ovatodiolide on mammosphere formation [26], while the phosphorylation of Hsp27 at Ser15 promoted its Ser78 phosphorylation and enhanced the nuclear localization of HER2 to induce Trastuzumab (TZMB) resistance in HER2+ breast cancer cells [27].