TP53 and mucoepidermoid carcinoma: In addition, a high expression of p53 is often observed in mucoepidermoid carcinomas (MECs) and higher-grade ACCs [8,9,10,11,12], while p53 modifications have been associated with the transformation process to a higher grade, often due to mutations of TP53, or heterozygosity loss on gene loci [8,9].