An A>G point mutation was engineered to change codon 522 in exon 8 from threonine to alanine (p.Thre522Ala). Alanine is non-phosphorylatable, rendering the protein constitutively inactive. A loxP site and an FRT site flanked selectable marker cassette were inserted into intron 7. The marker cassette was removed through subsequent flp-mediated recombination. (J:241351)