Transcription factor that may function downstream of PMK1 to regulate genes involved in infectious hyphae growth (PubMed:11952120). Is not essential for vegetative growth, conidiation or appressorium formation (PubMed:11952120). May be involved in the regulation of the expression of the cell surface sensor MSB2 (PubMed:21283781). Impairs pathogenicity on rice and barley leaves but does not affect appressorium formation (PubMed:11952120). However, fails to penetrate onion epidermal cells and to cause spreading lesions (PubMed:11952120). Reduces significantly the expression of the cell surface sensor MSB2 (PubMed:21283781). Belongs to the STE12 transcription factor family.