We examined the relative expression of RhoBTB1 and RhoBTB2 in a selection of human breast cancer cell lines (MDA-MB-231, T47D, MCF7) in comparison to two well-characterized normal human mammary epithelial cell lines – MCF10A [25] and HMT-3522 S1 [26]. This evidence concerns the gene RHOBTB1 and breast cancer.