An ACA to GCC change resulting in a threonine to alanine substitution at amino acid 906 (T906A) and an ACC to GCC change resulting in a threonine to alanine substitution at amino acid 1007 (T1007A) were inserted into exons 22 and exon 24, respectively. A loxP-flanked neomycin selection cassette inserted between exon 22 and 23 was removed via cre-mediated recombination. (J:265906)