PRC1 and breast cancer: Moreover, MYBL2 overexpression was observed in tamoxifen-resistant breast cancer cells associated with upregulation of BIRC5 (survival), hyaluronan-mediated motility receptor (HMMR) (metastasis), as well as PLK1 and protein regulator of cytokinesis 1 (PRC1) (proliferation), while suppression of MYBL2 re-sensitized cells to tamoxifen[101].