Exchange of GDP for GTP by Rap1A Authored: May, B, 2009-05-28 03:44:04 Edited: May, B, 2009-05-28 03:44:04 Epac1 and Epac2 are activated by binding cAMP and positively regulate the exchange of GDP for GTP by the small GTPase Rap1A. The downstream effects of Rap1A:GTP in beta cells are uncertain but may involve increasing the number of "restless newcomer" secretory granules near the plasma membrane and thereby increasing secretion of insulin.<br> Other effects of Rap1A :GTP may include regulating beta cell proliferation through activation of the Raf/MEK/ERK mitogenic cascade and activation of the PI3 Kinase/PDK/PKC cell growth pathway. Pubmed15569269 Pubmed15995848 Pubmed16973695 Pubmed17306374 Reactome Database ID Release 43381727 Reactome, http://www.reactome.org ReactomeREACT_18379 Reviewed: Gillespie, ME, 2009-06-02 00:59:01 Rap1-GTP Rap1-GDP