Flexible Accelerated STOP Tetracycline Operator (tetO)-knockin (FAST) was used to insert a construct containing a loxP site, FRT site, neo cassette, STOP, FRT site, tetracycline operator (tetO) and loxP site was inserted upstream of the translation initiation site. Flp-mediated recombination removed the neo/STOP cassette and left the tetO floxed and intact. Autoradiography confirmed a 20% reduction in protein expression. (J:137439, J:167659)