Figure 2

Scaffolds of the Raf/MEK/ERK cascade and regulation of KSR in mammals and in the nematode. SOC-2/SUR-8, CNK/CNK-1 and KSR are scaffolds of the Raf/MEK/ERK cascade. SOC-2/SUR-8 and CNK/CNK-1 are thought to facilitate Raf activation [52, 53]. KSR assembles Raf/MEK/ERK complexes and functions downstream of Raf. A) Protein interactions in mammals [22]. C-TAK1 and Nm23-H1 phosphorylate Ser392 of mammalian KSR, while PP2A is able to dephosphorylate the same residue. B) Genetic interactions in C. elegans. PAR-1 inhibits, while SUR-6/PP2A activates KSR-1. NDK-1 activates Ras signaling at the level of KSRs. The molecular mechanisms are not known. The regulation of KSR-2 remains to be determined. The mammalian proteins and their nematode homologs are labeled by the same color.