Three point mutations (R2130L, K2151E, and Y2154L) were introduced into exons 29 and 30 and an FRT flanked selection cassette was inserted via homologous recombination. Flp mediated recombination removed the neo cassette. The point mutations disrupt the Ras binding domain in the RA2 domain of the protein. Quantitative RT-PCR indicates that mRNA expression in homozygous mice is similar to wild-type controls.