Pharmacological inhibition of Sirtuins effects cell viability and induces apoptosis (A) PBMC purified from CLL patients were treated with indicated concentrations of EX-527 or sirtinol for up to 72 hr. Cell viability was measured by WST-1 assay following 24, 48 and 72 hr. incubation. Representative 3 patients are shown. (B) JVM3 and MEC-2 cell lines were treated with indicated concentrations of EX-527 and Sirtinol for up to 72 hr. Cell viability was measured by MTT assay following 24, 48 and 72 hr. (C) PBMC purified from CLL patients and (D) JVM-3 and MEC-2 cell lines were treated with indicated concentrations of EX-527 or sirtinol for 48 hr. Apoptosis was measured by annexinV/PI staining followed by flow cytometry and analyzed by FCS express software. The error bars represent SDs of mean and statistically significant differences (by Student t test) in between control and treatment are indicated by an asterisk (*, P< 0.01, **, P < 0.001; ***, P < 0.0001).