TP53 and cancer: It is now known that mutant p53 proteins not only lost their transcriptional function (loss of function), but also commonly obtain new function (gain of function).7 For instance, p53-R175H exhibits a gain of oncogenic function in driving cell migration and invasion.4, 8 Studies from animal models have confirmed that mice bearing a mutant p53 allele show more aggressive and metastatic tumor than p53 null.9, 10, 11 In human cancers, mutant p53 expression has been linked to poorer prognosis.12