Naringenin- and insulin-mediated phosphorylation of ERK1/2 is abolished by MEK1/2 inhibition and potentiated by MAPKp38 inhibition. HepG2 cells in serum-free media were preincubated (30 min) ± UO126 (10 μmol/l) or UO124 (10 μmol/l) (A), or ± SB203580 (10 μmol/l) or SB202474 (10 μmol/l) (B), followed by a 30-min incubation ± naringenin (100 μmol/l) or insulin (100 nmol/l). Total and phosphorylated ERK1/2 (Phos-ERK1/2)
were determined by immunoblotting, and the ratio of the phosphorylated form to total ERK1/2 is presented (relative to control)
as means ± SE for at least three experiments. *P < 0.05, **P < 0.01 compared with control; †P < 0.05, ‡P < 0.01 compared with naringenin or insulin.