BRCA1 and breast cancer: As shown in Fig. 2A,B, transfection of BRCA1 resulted in some increase of SIRT1 expression and a significant decrease of mTOR and Skp2/B protein expression in the cell lines MCF-7, T47D, SK-BR-3 and MDA-MB-157, suggesting that BRCA1 could activate the expression of SIRT1 in breast cancer.