Since the 13q34 amplification and/or CUL4A overexpression is more frequent in BRCA1-associated and basal-like primary breast tumors [12] we selected the BRCA1-null HCC1937 and the 13q34 amplified MDAMB157 cell lines to further characterize CUL4A function in breast cancer progression. This evidence concerns the gene BRCA1 and breast carcinoma.