Fig. 1. Multiple MAP kinase (MAPK) cascades using shared components regulate growth and differentiation in S. cerevisiae. Mating, invasive growth, pseudohyphal development, high-osmolarity/glycerol response and maintenance of cell wall integrity are each regulated by structurally similar but functionally distinct MAPK cascades that are activated by different upstream signals but have in common at least three kinds of kinases: a MAPKKK, a MAPKK (or MEK) and a MAPK. Yellow highlighting indicates the kinases that are shared by the different pathways. Note that for simplicity Ste50p is not shown in this figure (but see Fig. 2), although it associates with Ste11p and is required for optimal signaling through all of the pathways shown. Details can be found elsewhere (Gustin et al., 1998; Elion, 2000; Pan et al., 2000).
