Arginine codon 132 (CGA) in exon 3 was changed to histidine (CAC) (p.R132H) and a loxP site flanked STOP cassette (puromycin resistance gene, splice acceptor sequence and four copies of SV40 poly(A) signal sequence) was inserted into intron 2. This is a knockout allele and only after Cre-mediated removal of the STOP cassette will it express the mutated transcript and peptide.