A targeting vector was used to flank the entire gene with loxP sites and insert a Frt-flanked PGK-neomycin resistance cassette in reverse orientation. The gene was deleted by crossing these mice to a germline Cre strain, and subsequently mated to a line of germline Flp recombinase expressing mice, leaving a single loxP and an Frt site. No gene expression is detected by RNA-ISH.