Initially, we compared the transcript levels of HMGCR (regulator of cholesterol biosynthesis) and LDLR (cholesterol uptake), and ABCA1 and ABCG1 (involved in cholesterol efflux and maintenance of cellular cholesterol homeostasis and confirmed to be expressed in breast cancer) between treatment-insensitive (MCF7, BT474, T47D) and sensitive (SKBR3 and MDA-MB-231) cell lines following 48hrs exposure to atorvastatin. This evidence concerns the gene ABCG1 and breast cancer.