MCL1 and mantle cell lymphoma: Induced myeloid leukemia cell differentiation proteins (MCL-1), another member in the family of anti-apoptotic proteins with Bcl-2, is also another attractive target in blocking anti-apoptotic signaling in MCL [85,86,87]; however, there may be safety concerns with MCL-1 inhibitors due to potential cardiotoxicity based on early trial data [88].