Mcl1^tm1Yen

Two upstream promoter elements located at positions -87 (the SIE site) and -70 (the CRE-2 site) were targeted for mutation. The SIE and CRE-2 sites were replaced with BamHI and EcoRI restriction site, respectively, and a floxed neomycin resistance cassette was placed downstream of exon 1. Founder mice were crossed with EIIa-Cre transgenic mice to remove the neomycin cassette. Immunoblot analysis revealed gene expression was reduced by 90% in the thymus but was marginally or not at all affected in various other major organs examined, including liver, heart, lung and spleen. The altered expression was attributed to the lack of SIE and CRE-2 sites because expression was not disturbed in the thymus of mice homozygous for the same loxP insertion but with intact promoter elements. (J:146246)