HepG2 cells (Cell Bank of Chinese Academy of Sciences) were suspended in DMEM (BI, Israel) containing 10% fetal bovine serum (FBS; Gibco) and incubated at 37°C with 5% CO2. To evaluate the effect of luteolin on HepG2 cells, 5, 10, 20, 40, 80, 160, and 320 μmol/L luteolin (Sigma) was used. To determine the effect of ESR1 inhibition on HepG2 cells, 1, 20, 50, 100, 300, 500, and 900 nmol/L fulvestrant (Selleck China) was used. To determine the effect of Akt and MAPK-JNK signaling on ESR1 expression, Akt agonist SC79 (10 μmol/L, Selleck China), and MAPK-JNK agonist anisomycin (4 μmol/L, Selleck China) were used. DMSO served as a control.