However, weakly transcribing spontaneous TP53 mutations will be stimulated by the wild type XAF1 protein, killing the nascent tumor, but the same weak TP53 allele will produce a tumor when paired with an XAF-1 E134* polymorphism, which could enhance the frequencies of this class of TP53 mutations in the spontaneous and inherited cancers. The gene discussed is XAF1; the disease is neoplasm.