For instance, in a non-small-cell lung carcinoma cell line the demethylating agent decitabine (5-aza-2′-deoxycytidine) was able to increase PTEN mRNA levels, while knockdown of the DNA methyltransferase enzyme DNA (cytosine-5)-methyltransferase 3A (DNMT3A) in a hepatocellular carcinoma cell line resulted in demethylation of the PTEN promoter and upregulation of PTEN mRNA expression [130,131]. This evidence concerns the gene PTEN and hepatocellular carcinoma.