Fig. 3.

Genetic epistasis data indicate that cnk-1 promotes Ras signaling at a step of Raf activation after dephosphorylation of inhibitory sites in the regulatory domain (Reg.) and before activating phosphorylation in the kinase domain. This placement is distinct from sur-8, which is required upstream of the dephosphorylation event (45) and ksr-1 and sur-6, which are required downstream of activating phosphorylation in the kinase domain. ksr-1 and sur-6 could also have additional, upstream requirements. Circled P, phosphate group.