CP and infection: Interestingly, a fungus-secreted protein, the cerato-platanin protein (CP), acts as a MAMP to elicit plant defense responses (Djonovic et al., 2006; Seidl et al., 2006; Yang et al., 2009; Frias et al., 2011), but S. sclerotiorum CP1 (SsCP1) interacts with PR1, overexpression of which shows more resistance to S. sclerotiorum, in the apoplast to facilitate infection by S. sclerotiorum (Yang et al., 2018).