Receptors mediated changes in ERK1/2 and ERK5 phosphorylation.

<p>(<b>A</b>) HEK-293 cells expressing SSTR4 and /or δOR were treated as indicated for 15 min at 37°C and cell lysate was subjected to Western blot analysis. In SSTR4 monotransfected cells, SST and SSTR4 agonist resulted in inhibition of phospho-ERK1/2 when compared to control, whereas, δOR activation was without any significant effect on ERK1/2 phosphorylation. (<b>B</b>) In cotransfected cells, SSTR4 activation displayed increased ERK1/2 phosphorylation. In presence of δOR agonist alone or in combination with SST or L-803087, ERK1/2 activation was decreased although remained significantly higher than control. (<b>C</b>) In monotransfected cells, SSTR4 activation resulted in enhanced phospho-ERK5 expression, whereas, no change in the phospho-ERK5 levels was observed upon δOR activation. (<b>D</b>) In cotransfected cells, increased ERK5 phosphorylation was observed upon SSTR4 or δOR activation alone or in combination. Note that the combined agonist treatment had pronounced effect on ERK5 phosphorylation. Densitometric analysis for the blots (in Panels A-D) was performed by using β-actin or total as loading control and data analysis was done by using ANOVA and <i>post hoc</i> Dunnett’s to compare against basal level (*, <i>p</i><0.05).