MYC and lymphoma: Western blot analysis showed that treatment with APR-246 caused an increase in the levels of the pro-apoptotic BH3-only protein PUMA, a critical initiator of apoptosis mediated by TRP53 [43], in both the wt TRP53 Eμ-Myc lymphoma cells and their TRP53 deficient derivatives, although to a greater extent in the former (Fig. 4b).