TP53 and neoplasm: Various mechanisms have been proposed to explain how the mutated TP53 protein contributes to tumor formation, including loss of TP53 tumor suppressor function and consequently the dysregulation of its target genes, the “dominant negative” effect in which the mutated TP53 protein inhibits wild-type TP53 protein and the “gain-of-function effect” in which the altered TP53 protein acquires new oncogenic properties.