PROX1 and breast carcinoma: Epigenetic silencing is one of the mechanisms responsible for PROX1 inactivation in tumors.22,23 Hypermethylation of CpG islands was identified as a mechanism for PROX1 inactivation in breast carcinomas and carcinomas of the biliary system.22,23 This encouraged us to investigate if PROX1-decreased expression in OSCC was related to promoter DNA methylation.