In summary, the present study indicates that: (a) the Bim protein is dispensable for proapoptotic response to BITC in breast cancer cells; (b) PUMA induction and downregulation of Bcl-xL protein contribute to BITC-induced apoptosis, which is not a cell line-specific phenomenon; (c) BITC treatment differentially affects the levels of Bcl-2 protein in MCF-7 versus MDA-MB-231 cells; and (d) PUMA deficiency in HCT-116 human colon cancer cell line increases its sensitivity to BITC-induced G2/M phase cell cycle arrest. This evidence concerns the gene BCL2L1 and breast cancer.