A targeting vector was created with a CMV enhancer/chicken beta-actin core promoter (pCA) upstream of the MADM G-tTA2 cassette. The MADM G-tTA2 cassette used here (GFPN-terminus-intron-tTA2ATG-less) was designed with the N-terminal portion of a mutant enhanced green fluorescent protein (mut4EGFP first exon; nucleotides 1-274), a beta-globin intronic sequence (containing a frt-flanked region of two lox site variants [lox2272 and lox5171] and then a loxP-flanked neomycin resistance gene), an ATG-less tetracycline-regulated transactivator sequence (tTA2ATG-less), and an SV40 T-antigen poly(A) signal. This entire construct was subcloned into the pROSA26-PA targeting vector to generate the final targeting construct pROSA26-G-tTA2. The pROSA26-G-tTA2 construct was inserted into the Gt(ROSA)26Sor locus. (J:181830)