As cancerous mast cells (MC) in aggressive systemic mastocytosis (ASM) and mast cell leukemia (MCL) were found to express the anti-apoptotic Mcl-1, Bcl-2, and Bcl-xL, Peter et al. (2014) decided to examine the effects of obatoclax (GX015-070), the pan-Bcl-2 family blocker on human and canine mastocytoma cell lines [60]. The gene discussed is BCL2; the disease is mast cell leukemia.