MMP9 and hepatocellular carcinoma: In our study, upregulated E-cadherin and downregulated N-cadherin, Vimentin and MMP9 induced by knockdown or inhibition of TDO2 were observed in HCC cells, as well as a negative correlation between TDO2 and E-cadherin and a positive correlation between TDO2 and N-cadherin in HCC samples, suggesting that TDO2 overexpression promoted HCC metastasis through inducing EMT in HCC cells.