Figure 1

Figure 1 Overview of the RAS-MAPK pathway and associated disorders. Binding of a growth factor to a receptor tyrosine kinase (RTK) activates RAS proteins by the action of guanosine nucleotide exchange factors (GEFs) such as SOS which catalyse guanosine nucleotide exchange. RAS-GTP activates RAF and downstream effectors. Signalling is terminated when RAS-GTP is hydrolysed to RAS-GDP either by the action of GAPs neurofibromin or p120 GAP. Responsible proteins for autoimmune lymphoproliferative syndrome (ALPS), capillary malformation-arteriovenous malformation (CM-AVM), neurofibromatosis type 1 (NF1), Costello, Noonan, LEOPARD, cardiofaciocutaneous (CFC) and NF1-like syndrome are indicated.