Muc1^{tm1.1(cre/ERT2)Lcm}

This allele was derived by crossing mice bearing Muctm1(cre/ERT2)Lcm to Gt(ROSA)26Sortm1(FLP1)Dym mice to delete the frt site-flanked neomycin resistance cassette in the germline. The present, neo-, allele contains, downstream of the termination codon of the endogenous gene, an internal ribosomal entry site (IRES) followed by DNA encoding Cre recombinase joined to ERT2 and a single frt site (IRES-CreERT2-FRT). ERT2 is a triply mutated (G400V, M543A, L544A) human estrogen receptor ligand-binding domain (LBD) that renders the fusion protein highly sensitive to activation by 4-hydroxytamoxifen, but unresponsive to the receptor's native ligands. The cre/ERT2 fusion protein is expressed under control of the endogenous promoter without disrupting expression of the endogenous gene. Tamoxifen-induced Cre activity has been demonstrated in acinar and ductal cells of the adult pancreas and in their embryonic precursors. (J:159445)