A full-length Gli1 cDNA followed by sequence for a C-terminal 3X FLAG tag, an IRES, the Venus fluorescent reporter gene, an intron and poly(A) signal sequences were inserted into the locus downstream of a splice acceptor and loxP site flanked neomycin resistance gene cassette. Upon cre expression, the neo cassette is removed and FLAG tagged Gli1 gene and Venus gene expressed. (J:121411)