A loxP site was inserted upstream of exon 2 and an FRT-flanked neomycin selection cassette and second loxP site were inserted downstream of exon 2. The selection cassette was removed via flp-mediated recombination, leaving exon 2 floxed. Deleting exon 2 preserves the native start codon and abolishes both isoforms of Cnksr2. (J:339544)