It is interesting that PI3-kinase levels are higher in highly invasive and metastatic breast cancer cell line MDA-MB-231 cells compared to nonmetastatic MCF-7 cells (Sliva et al, 2002), which can explain for LY294002-induced stabilisation of ERα in MDA-MB-231 cells overexpressing ERα. This evidence concerns the gene ESR1 and breast carcinoma.