Monovalent and bivalent IAP antagonists have been demonstrated to induce cancer cell death in vitro and in vivo and several compounds are in development for the treatment of cancer.15,30 Lalaoui et al.46 recently demonstrated that birinapant (B1) treatment with the p38 inhibitor, LY2228820, was well-tolerated and increased cancer cell death in a highly aggressive oncogenic NRas mutant model of AML. Here, NRAS is linked to acute myeloid leukemia.