Figure 1.

Functional relevance of SOS1/2 GEFs in physiological RAS signaling pathways and RASopathies. (A) Schematic representation of RAS and RAC activation/deactivation cycle mediated by SOS1/2 GEFs and GAPs, respectively. (B) Differential participation of SOS1 and SOS2 in downstream RAs signaling as suggested by current experimental evidence. (C) SOS2-specific mutational landscape in human RASopathies (Noonan syndrome, NS9 type). HD: histone domain; DH: Dbl homology; PH: pleckstrin homology; CDC25H: cell division cycle 25 homology; REM: RAS exchange motif; PR: proline-rich.