SLC22A1 and hepatocellular carcinoma: Since SNU398 and SNU449 cell lines are often used in HCC related studies [44, 45], and the SLC22A1 expression of these two cells have been verified higher in SNU398 and lower in SNU449 which can represent the function of SLC22A1 at different expression levels, as well as the well cultured of these two cell lines in our laboratory, we finally choose these two cell lines to conduct further experiments.