cIAP1 potentiates MYC activity, by ubiquitinating its negative regulator, MXD1.12 We therefore hypothesized that LCL-161 would show potent activity in the Eμ-Myc model of aggressive lymphoma, which is sensitive to a range of novel apoptosis-inducing stimuli.13, 14, 15, 16 Unexpectedly, Eμ-Myc lymphomas were highly resistant to LCL-161-induced apoptosis in vitro, despite engagement of IAP degradation and NFκB activation at ‘on-target' concentrations. Here, MXD1 is linked to lymphoma.