Alanine amino acid substitutions were introduced to phosphorylation sites serine 831 (S831A) and serine 845 (S845A) in exon 17 of the gene. A floxed neomycin resistance cassette was inserted upstream of exon 17 for positive selection. Mutant animals were crossed to cre deleter strain Tg(CMV-cre)1Nagy to removed the floxed neo cassette, leaving behind the 2 amino acid substitutions. The targeted mutation was confirmed using immunoblot with phosphorylation site-specific antibodies.