This allele is derived from Hcsttm1Cln by mating mutant animals to cre deleter strain TgN(CMV-cre)1Cgn. Resulting progeny are deleted for the floxed neo cassette and contain a single loxP site in place of exon 1 and intron 1. Absence of gene expression in homozygous mutant animals was confirmed by Western blot analysis of lysates from NK cells and CD8+ cells. (J:80426)