To investigate the expression of endogenous MTSS1 and SCAMP1 in breast cancer cell lines, we performed immunoblotting (IB) using whole-cell extracts from SkBr3 and MDA-MB-453 (HER2+/ER−/PR−) and BT-474 (HER2+/ER+/PR+) human breast cancer cells. This evidence concerns the gene PGR and breast cancer.