Fig. 2.

Structures of the various modified Cpr alleles and strategy for conditional deletion or rescue of the Cpr gene. Arrowheads represent LoxP sequences and indicate orientation. Selected exons are numbered at the top of the gene structure schematic. Insertion of the floxed neomycin-resistance gene (neo) in the last Cpr intron leads to the generation of a hypomorphic (Cpr ^low) or a reversible hypomorphic (rCpr ^low) allele, with global decreases in Cpr expression. Cre-mediated deletion of the Cpr exons 3–15 from the floxed Cpr (Cpr ^lox) allele or the Cpr ^low allele leads to conditional Cpr deletion in cells expressing Cre (Cpr ^null), whereas Cre-mediated deletion of the floxed neo from the rCpr ^low allele leads to conditional Cpr rescue in cells expressing Cre, regenerating the wild-type Cpr (Cpr ⁺) allele.