In vivo anti-tumor activity has been shown for silvestrol in hematological malignancies such as chronic lymphocytic leukemia, acute lymphocytic leukemia and mantle cell lymphoma [16-18], likely through the depletion of short half-life pro-growth or pro-survival proteins including cyclin D and Mcl-1. Here, MCL1 is linked to B-cell chronic lymphocytic leukemia.