By analogy with the typical signal transduction systems in procaryotes and eucaryotes, it is tempting to speculate that Afsk2 autophosphorylates its serine and threonine residues upon sensing high osmolality, then transfers the signal to the putative target protein by means of phosphorylation, and the phosphorylated target protein activates the expression of multiple genes required for aerial mycelium formation at high osmotic pressure.