Sirt1/2-IN-2 (compound hsa55) is a dual inhibitor of SIRT1/2 with IC 50 s of 1.8 μM ( SIRT1 ) and 2.4 μM ( SIRT2 ), respsectivley. Sirt1/2-IN-2 completely blocks p53 deacetylation, and increase of p53 and α-tubulin acetylation. Sirt1/2-IN-2 induces apoptosis and shows anti-proliferation activity against human leukemia cell lines.