SIRT7 and posterior cortical atrophy: To identify the specific SIRT isoform related to PCa progression, we examined the expression level of SIRT family proteins (SIRT1 through SIRT7, except SIRT4) in four representative PCa cell lines, including androgen-dependent LNCaP and LNCaP-LN3 cells and androgen-independent PC-3 and PC-3M cells (Figure 1A).