Exon 41 was replaced with one containing GAC to GCA nucleotide substitutions which results in an aspartate to alanine change at amino acid 2017 (D2017A). A loxP and frt-flanked PGK-neomycin cassette were inserted into intron 41 and another loxP site was inserted in intron 42. Flp-mediated recombination removed the neomycin cassette. This is a loss-of-kinase function mutation. (J:234639)