SIRT1 and carcinoma: In normal mammary tissue cells, in benign tumor cells, and in low malignancy grade carcinomas (G1 carcinomas), SIRT1 immunoreactivity had strong throughout and was preferentially nuclear; on the other hand, in less differentiated, highly malignant cancer cells (G2–G3 carcinomas), SIRT1 immunoreactivity was generally weaker but shifted to cytoplasmic localization, as shown on tissues in IHC.