Fig. 6. ERK1/2 activity contributes to the short-term glucose-induced insulin secretion in B1 cells. (A) Western blot analysis of the inhibitory effect of PD98059 on the activation (by phosphorylation) of ERK1/2 after 10 mM glucose stimulation in B1 cells. (B) Insulin secretion by B1 cells treated with PD98059 at three different time points. After 5 minutes glucose stimulation (top), B1 cells display a 60% decrease in their secretory response as compared to control DMSO-treated cells (^*P<0.05). However, after 15 minutes stimulation (middle), the decrease in insulin secretion is reduced to 30% (^**P<0.02), and is not present after 30 minutes glucose stimulation (bottom). Data in all cases are mean ± s.e.m. for basal and stimulated % insulin secretion (left panels) and secretion fold-stimulation (right panels) of three replicates of a single experiment. Stimulation conditions of 0 to 10 mM glucose were used to facilitate direct comparison with previously published work showing the effect of glucose-dependent ERK1/2 activation on insulin secretion (Longuet et al., 2005).