While previous findings have shown that both RP-Mdm2 and p19Arf-Mdm2 signal to p53 and similarly suppress Myc-induced B cell lymphoma [11], [19], our data presented here suggest that disruption of RP-Mdm2 signaling does not accelerate APT121-induced prostate cancer. This evidence concerns the gene MDM2 and B-cell non-Hodgkin lymphoma.