Since GalCer is a substrate for GAL3ST1 and a precursor molecule for sulfatide, in the present study we analysed the resistance of breast cancer MDA-MB-231 cells with overexpression of sulfatide (MDA.SUL) cells and sulfatide-negative control MDA-MB-231 (MDA.C) cells to doxorubicin-induced and hypoxia-induced apoptosis. This evidence concerns the gene GAL3ST1 and breast cancer.