Update publication information The extensive drug resistance of hepatocellular carcinoma (HCC) has become the main cause of chemotherapy failure. The mechanisms leading to drug resistance in tumor cells are not well understood. Previous studies demonstrated that plasma membrane proteins play important roles in mediating drug disposal or pharmacokinetics. Therefore, we performed proteomic studies on the composition of 5-fluorouracil (5-Fu) resistant Bel/5Fu cell line and its parent Bel7402 cell line by using an ionic liquid-assisted proteins extraction method with the advantage of extracting plasma membrane proteins to a greater extent. In total, 4,532 unique proteins were quantified and 103 proteins (>2-fold change, p-value <0.05) including 25 plasma membrane proteins showed to be differentially expressed in Bel/5Fu compared with Bel7402. Western blot analysis results were further confirmed that the plasma membrane proteins EPHX1 PLIN2 RAB27B SLC4A2 were up-regulated in Bel/5Fu cells in accordance with the proteomics data. Moreover, cell viability assay and clonogenic survival assay results demonstrated that EPHX1 are closely related to the chemoresistance of Bel/5Fu to 5Fu.