Protein kinase that acts downstream of the MPS1 MAPK cascade as a highly conservative signal modulator that dictates growth, conidiation and pathogenicity (PubMed:28424497). Phosphorylates HAT1 at 'Ser-8' to block its translocation from the nucleus to the cytoplasm where HAT1 positively regulates appressorium development and pathogenicity (PubMed:30776962). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] Mainly localizes to the cytoplasm at the conidial stage. Expression is regulated by MPS1 MAP kinase, particularly under stress conditions. Leads to significant delay in mycelial growth, complete loss of conidiation and inability to penetrate the host surface by mycelia-formed appressorium-like structures, consequently resulting in loss of pathogenicity. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. GSK-3 subfamily.