Exons 24 and 25, encoding amino acids in the carboxyl-terminal cytoplasmic domain (residues 1065 through 1137), were replaced with a neomycin selection cassette. Northern blot analysis of salivary gland total RNA showed normal levels of a truncated transcript. RT-PCR analysis, using probes flanking the targeted region indicated a deletion of 195 coding-nucleotides in mutant mice. (J:60671)