BAG1 and breast cancer: Increased levels of Bcl-xL expression were found in a subset of primary human breast carcinomas, mainly in undifferentiated histological grade (HG) III tumors.67,68 In the breast, their overexpression could protect breast cancer cells from p53-mediated apoptosis.69 More recently BAG-1, a multi functional protein that blocks apoptosis, has been correlated with improved survival in early stage breast cancer.