The 5'UTR, exon 1, and exon 2 wwere replaced with a construct containing (5' to 3') an frt flanked neo cassette, tetracycline responsive (tetO/TRE) promoter, a myc-tagged Sod2 cDNA, and an IRES-EGFP. The absence of protein expression was confirmed by western blot analysis on embryonic fibroblast. (J:162190)