One further strategy to counteract Bcl-2 family members is the monoclonal antibodies which target the tetra-span membrane protein CD20 (Rituximab) but can also downregulate expression of Bcl-2 family members, Mcl-1 (intrinsic pathway) and XIAP (convergence pathway) in certain leukemias, providing yet another example of unexpected links to apoptosis pathways through receptor-mediated signaling [113]. This evidence concerns the gene BCL2 and leukemia.