A loxP site was inserted usptream of exon 1. An FRT-flanked neo cassette with a 3' loxP site was inserted downstream of exon 1. Cre-mediated recombination removed exon 1 and the neo cassette. Semi-quantitative RT-PCR confirmed reduced transcript expression in the retina, kidney, liver, spleen and testis. This allele is hypomorphic. (J:185135)