AZ-Tak1 is a potent and a relatively selective inhibitor of TAK1 kinase activity, with an IC50 of 0.009 mM. AZ-Tak1 treatment decreased the level of p38 and ERK in mantle cell lymphoma cells, and induced apoptosis in a dose and time dependent manner, with an IC50 of 0.1–0.5 mM. Using the annexin-V and PI staining and FACS analysis, After 48 hours of incubation, AZ-Tak1 (0.1 mM) induced apoptosis in 28%, 34% and 86% of Mino, SP53, and Jeko cells, respectively, which was increased to 32%, 42%, and 86% when 0.5 mM concentration was used.