passages.id: split_4_test_720_passage
passages.type: progene_text
passages.text: Activation of the ERK / MAPK pathway by an isoform of rap1GAP associated with G alpha(i) Many receptors for neuropeptides and hormones are coupled with the heterotrimeric G ( i ) protein , which activates the p42 / 44 mitogen - activated protein kinase ( ERK / MAPK ) cascade through both the alpha - and betagamma - subunits of G(i) .