TP53 and neoplasm: Using a mouse model of the Δ133p53α isoform (Δ122p53), we previously showed that the isoform had powerful tumorigenic and inflammatory functions, and in heterozygous mice, could partially inhibit the tumor-suppressor activities of wild-type p53.19 In this paper, we report that Δ122p53 enhanced the tumor-suppressor activities of the attenuated p53 mutant mΔpro.