A C1184T transition was inserted into exon 3 to create an A286V substitution in the eighth transmembrane domain. A neo was inserted into intron 2. Northern blot of mutant skin samples indicated that the presence of the neo caused impared splicing of exon 2 to exon 3, with an abnormal band compprising ~40 and 60% of the total transcript in hetero- and homozygous animals, respectively. (J:97104)