MAP Kinase Cascade
The MAP kinase cascade is a signalling cascade that occurs on the activation of FLS2. FLS2 could be activated by Flg22 binding. Through the phosphorylation of kinases, a WRKY transcription factor is activated (although there are potentially other pathways operating in parallel that are yet to be identified), changing gene expression levels in the cell. There are various different protein kinases involved in this cascade, and due to their complexity they have been studied less than comparable pathways in humans and fungi. MAP kinase cascades mediate osmotic shock, oxidative stress, cold responses, and anti-pathogen responses.
The kinases involved in the MAP kinase cascade, mitogen-activated protein kinases, are activated by a mitogen. This is a bioactive protein or peptide, inducing cell division. The mitogen triggers signal transduction via a MAP kinase cascade.
Refs: mostly Wikipedia (https://en.wikipedia.org/wiki/Mitogen-activated_protein_kinase#Signaling_cascades; https://en.wikipedia.org/wiki/Mitogen)