A loxP site was inserted into intron 1 and a floxed hsv-tk and pgk-neo cassette was inserted into intron 7. Cre mediated recombination removed the hsv-tk and pgk-neo cassette and exons 2 -7, leaving a single loxP site. Western blot analysis confirmed the absence of protein expression in cerebellar lysates from homozygous mice. (J:150460)