Figure 1.

A general model of MAPK cascade functioning in plant development. A typical MAPK cascade contains three signaling components: a MAPK kinase kinase (MAPKKK), a MAPK kinase (MAPKK), and a MAPK. The MAPK cascade is activated by upstream regulators and transduces the signal to downstream transcription factors in the nucleus via sequential phosphorylation. The red dots represent extracellular signals that can be perceived by membrane-anchored receptors. The black arrow indicates gene expression. P, phosphorylation relay. TF, transcription factor.