They are V600 in Serine/threonine-protein kinase B-Raf (encoded by BRAF), and R88 and C420 in the phosphatidylinositol-4,5-bisphosphate 3-kinase encoded by PIK3CA. We found both C420 and R88 to be positions of mutational hotspots in endometrium, colon and breast cancer. This evidence concerns the gene PIK3CA and breast cancer.