HepG2 cells were treated with 100 nM ATV and 400 nM DXM for 3 days to verify the effects of DXM on OATP1B1 transport function in HepG2 cells and the underlying mechanism. The CCK-8 assay showed that 100 nM ATV and 400 nM DXM had no cytotoxicity in HepG2 cells (Figure 5A). We found that in the ATV group, the uptake of ATV by HepG2 cells was 5.307 ± 0.5764 ng/mL, and in the ATV+DXM group was 2.163 ± 0.3038 ng/mL by measuring the ATV concentration in cell lysis through LC-MS/MS. Compared with the ATV group, the concentration of ATV was decreased by 59.24% in the ATV+DXM group (Figure 5B, **P < 0.01). These results can explain the increasing concentration of ATV in plasma. Compared with the control and ATV groups, the protein expressions of OATP1B1 and LXRα were decreased in the DXM and ATV+DXM groups (Figures 5C–E, *P< 0.05). Therefore, DXM could suppress ATV uptake in HepG2 cells and DXM may downregulate the protein expression of OATP1B1 via LXRα.