A neomycin resistance cassette replaced part of an exon of the gene that corresponds to amino acids 114 to 230 in the reported human sequence, and an adjacent intron. Northern analysis using a murine cDNA probe did not detect transcript in cultured keratinocytes from homozygous mutant mice. Immunoprecipitation studies using antiserum raised against the cytoplasmic domain of human did not detect protein in lysates of cultured keratinocytes from homozygous mutant mice. (J:59991)