A Pgk-neomycin resistance cassette replaced 1.65kb of sequence that includes the first four exons of the gene. RNA in situ hybridization analysis did not detect transcripts in olfactory sensory neurons of 5-day old homozygous mutant mice. Immunohistochemistry analysis showed reduced staining on olfactory bulb sections derived from 5-day old homozygous mutant mice. (J:45534)