Fig. 3.

Activation of the MEK, p38 MAPK, and JNK signaling pathways by L-arginine in HepG2 cells. (A) MEK1 and p-MEK1/2 expression levels. (B) p-ERK1/2, p-p38 MAPK, JNK, and p-JNK expression levels. (C) The mRNA expression levels of IGF-1 and IGFBP-1 expressions in HepG2 cells treated using a 20-µM MEK inhibitor PD98059, 20-µM p38 MAPK inhibitor SB203580, or 20-µM JNK inhibitor SP600125. Arg, 10 mM L-arginine. *P < 0.05; **P < 0.01 versus the control group for the ANOVA test. The expression levels of IGF-1 and IGFBP-1 were tested using the t-test