Exon 3 was floxed and an FRT flanked neo cassette was inserted within intron 3 by homologous recombination. Exon 3 is deleted by cre mediated recombination which eliminated the catalytic domain and also caused a frameshift mutation and early termination of the protein. Loss of function was confirmed by in vitro kinase assay as well as PET and CT imaging with labeled probes. (J:158373)