Overall, these results strongly indicate that caspase-6 and caspase-7 signals are required for the induction of cell apoptosis by combination of ω-3 FFAs and ATRA in three subtypes of breast cancer cells, while caspase-3 might also be involved in the induction of cell apoptosis in SK-BR-3, HCC1806 and MDA-MB-231 cells. Here, CASP7 is linked to breast cancer.