Many HDAC inhibitors have already shown remarkable antitumor activities in the clinical and preclinical settings.However, their clinical efficacy is limited because of unfavorable toxicities associated with their broad range HDAC inhibitory effects.Isoform-selective HDAC inhibition may allow for anti-lymphoma activity without unwanted side effects and novel target for lymphoma therapy.Mantle cell lymphoma (MCL) is a subtype of B-cell Non-Hodgkin ' s lymphomas often associated with unfavorable outcome.In spite of these important advances, a fundamental obstacle to improve MCL therapy is the intrinsic characteristic of MCL to relapse and drug resistance.Recently, we have identified HDAC3 as a critical player in the regulation of survival/apoptosis,microenvironment-mediated drug resistance and MCL aggressive progression.Our studies to date have shown the following: 1.