Figure 4: Effect of mollugin on phosphorylation of MAPK (a), activation of Nrf2 (b), and expression of HO-1 (c) in OSCCs. Effects of MAP kinase inhibitors on mollugin-induced activation of NF-κB, Nrf2, and HO-1 (d). Cells were treated with 40 μM mollugin for indicated times (a)–(c). Cells were pretreated with the p38 inhibitor SB203580 (20 μM/L), the ERK inhibitor PD98059 (20 μM/L), or the JNK inhibitor SP600125 (20 μM/L) for 1 hour and treated with 40 μM mollugin for 30 min (MAPK, Nrf2, and NF-κB) or 3 days (HO-1). The results are representative of three independent experiments.