ESR1 and breast carcinoma: Also, human triple-negative breast cancer cell lines such as BT549, MDA-MB-436, DU-4475 and MDA-MB-468 cells showed significantly lower expression of SMURF2 protein, compared to ER + or HER2+ cell lines (112), indicating that SMURF2 might play an inhibitory function in the context of breast cancer invasion and metastasis.