In the presence of MAG, Rap1GAP1 levels are increased, which leads to inactivation of Rap1 and inhibition of neurite outgrowth. Conversely, when intracellular cAMP is elevated, Rap1GAP1 levels are reduced and this leads to an increase in Rap1 activity, which facilitates neurite outgrowth. Activation of EPAC can also increase neurite outgrowth, but only in response to priming with agents such as 8-CPT.