Cell-permeable. ITSA-1 is a suppressor of Trichostatin A (TSA) and a molecular tool for dissecting gene regulation by distinct acetylation events (histone and tubulin). ITSA-1 specifically suppresses TSA inhibition of HDAC (histone deacetylase), but not other HDAC inhibitors. ITSA-1 reverses TSA induced histone acetylation, overall deacetylation. ITSA-1 also reverses TSA induced cell cycle arrest and apoptosis.