TP53 and cancer: The truncated isoforms of p73 (Np73) which is a putative antagonizer of p53 function was found to be overexpressed in several cancers.79 The first report on the expression of p63 and p73 proteins in RB was reported by Adithi et al. 80 They reported that p63, p73, and their delta isoforms (truncated forms) were expressed in more than 50% of tumor samples.