A loxP site was inserted upstream of exon 1 and an FRT site flanked neomycin resistance gene cassette and a second loxP site downstream of exon 2. Also inserted downstream of exon 2 was a cDNA for the endogenous gene where a point mutation was engineered to change aspartate codon 34 into an asparagine codon (p.D34N or p.Asp34Asn). The neo cassette was removed through subsequent flp-mediated recombination and exons 1-2 (comprising the entire gene) were deleted through subsequent cre-mediated recombination. This leaves the mutated cDNA which codes for a kinase-dead version of the protein.