In human breast cancer cells, high levels of GRP78 confer resistance to estrogen starvation-induced apoptosis via an inhibition of the BCL2-interacting killer (BIK), a pro-apoptotic BH3-only protein, and the induction of three anti-apoptotic molecules: B-cell lymphomas BCL2, BCL-XL, and BCL-W. This evidence concerns the gene BIK and breast cancer.