MAPK8 and cancer: After binding of the GnRH-antagonist, native GnRH-II, or GnRH-II-agonist, it couples to G protein αi and activates the signal transduction mechanisms described for the GnRH-I-R in human cancers including inhibition of autophosphorylation of the EGF-receptor and phosphorylation of JNK [54,55,57,58] (Figure 2).