BAG1 and breast carcinoma: To assess the role of Bag-1 on cell viability and apoptosis, MCF-7 breast cancer cells were transfected with Bag-1 expression vector or Bag-1 siRNA (Fig. 1b), and cell viability (Fig. 1c) and apoptotic cell death (Fig. 1d) were monitored for a period of 72 h.