This allele is a derivative of Kittm1Bsm in which a Cre mediated recombination event removed the neomycin cassette. Excision of the neomycin cassette restores normal Kit expression. The resulting heritable mutation, Y719F, was designed to prevent the binding of SH2 domain proteins including the p85 subunit of the PI 3-kinase and to abolish subsequent signaling events.