TP53 and endometrioid adenocarcinoma: Zaidi et al. found IMP3 positivity in 64% of endometrial serous carcinomas and 19% of grade 3 endometrioid carcinomas using 5% cut-off for positivity, and suggested a panel of p53, p16, IMP3, ER and PR as best for distinguishing serous from endometrioid carcinoma [18].