MSB2 and SHO1 have overlapping functions in recognizing various surface signals for MAPK PMK1 activation and appressorium formation (PubMed:21283781). While MSB2 is critical for sensing surface hydrophobicity and cutin monomers, SHO1 may play a more important role in recognizing rice leaf waxes (PubMed:21283781). Forms homooligomers. Expression is significantly reduced when PMK1 is disrupted. Reduces only slightly appressorium formation and virulence. Belongs to the SHO1 family. Truncated N-terminus.