HIF1A and breast carcinoma: However, BRD7 was found to function as a tumor suppressor in breast cancer whether in ER-positive breast cancer MCF-7 cells or ER-negative MDA-MB-231 and MDA-MB-453 cells, supporting that BRD7 function as tumor suppressor independent of ER but other mechanism, including the regulation of BRD7 on HIF1α.