NONSENSE MUTATIONS IN THE C-TERMINAL SH2 REGION OF THE GTPASE-ACTIVATING PROTEIN (GAP) GENE IN HUMAN TUMORS

GTPase Activating Protein (GAP) is involved in down-regulating normal ras proteins and in the signal transduction pathway of some growth fac tors. We have screened 188 human tumours for mutations in the catalyti c domain and at the C terminal SH2 region GAP. Three nonsense mutation s in basal cell carcinomas were detected in the SH2 region and no muta tions could be demonstrated in the catalytic domain. We conclude that mutations in the SH2 region of GAP may play a role in tumorigenesis an d that inactivating mutations of the GAP catalytic domain do not contr ibute to tumour development.