A mast cell degranulating peptide that increases GTPase activity for Gi and Go signaling, binds calmodulin (Kd 0.3 = nM), inhibits the calmodulin-induced activation of phosphodiesterase (IC50 = 0.02 μM), and kills leukemia, myeloma, and breast cancer cells (IC50s = 8-9.2, 11, and 20-24 μM, respectively)