Mitogen-activated protein kinase adapter protein; part of the MST11-MST7-PMK1 MAP kinase (MAPK) cascade that is essential for appressorium formation, penetration and invasive growth (PubMed:15749760, PubMed:23454094). Binds to the MAPKKK MST11 and the MAPKK MST7 to maintain the stability of the MST11-MST7 complex for the phosphorylation of the MAPK PMK1 (PubMed:15749760). Is also involved in the MPS1 and OSM1 MAPK pathways, and especially plays a role in the activation of MPS1 in response to cell wall stress (PubMed:28244240). Its function differs in the 3 MAPK pathways (PubMed:28244240). Interacts with MST7 and MST11 (PubMed:15749760). Interacts with MCK1, MKK2 and HIK1 (PubMed:28244240). The sterile alpha-motif (SAM), but not the Ras-association domain, is important for its interaction with MCK1 and responses to cell wall and oxidative stresses. Impairs the formation of appressoria and the ability to infect rice plants (PubMed:23454094). Leads to reduced MAPK MPS1 activation under stress conditions (PubMed:28244240). Affects OSM1 phosphorylation in response to hyperosmotic stress (PubMed:28244240).