Fig. 5.

Effect of PAL on the insulin secretion in INS-1 cells (a) INS-1 cells were incubated with different doses of PAL (0 μg/ml, 10 μg/ml, 20 μg/ml) for 48 h. The insulin secretion was determined upon the glucose stimulation, and then normalized to the protein concentration. b PA- induced cells were respectively incubated with PAL (20 μg/ml), ERK inhibitor PD98059 (10 μM), and JNK inhibitor SP600125 (10 μM). The insulin secretion was subsequently assessed upon glucose stimulation, and then normalized to the protein concentration. Values are expressed as mean ± SD. n = 3.*P < 0.05, **P < 0.01, *** P < 0.001, **** P < 0.0001