Activation of MAP kinase by MC4-R through PI3 kinase.

The melanocortin 4 receptor (MC4-R) is a Galpha s-coupled receptor known to increase cAMP production following agonist stimulation. We demonstrate that the mitogen-activated protein kinases p42 (ERK2) and p44 (ERK1) are also activated by MC4-R following treatment with the MC4-R agonist NDP-alpha-MSH in stably transfected CHO-K1 cells. This time- and dose-dependent response is abolished by the MC4-R antagonist SHU-9119.