The results presented here reveal that PROX1 overexpression inhibits in vitro cell proliferation of OSCC, which corroborates with previous results in other tumor cells from esophageal squamous cell carcinoma and hepatocellular carcinoma.18,40 Under normal development, this gene has been associated with the regulation of cell proliferation by downregulating cell cycle inhibitors CDKN1B (p27) and CDKN1A (p21).13 In this study, PROX1 overexpression reduced cyclin D1 expression, without interfering with p53 and p21 expression. This evidence concerns the gene PROX1 and hepatocellular carcinoma.