The transgenic construct consists of the ubiquitous promoter CAG, composed of the cytomegalovirus (CMV) immediate early enhancer and the modified chicken b-actin promoter, a loxP-flanked transcription STOP cassette (LSL) followed by the cDNA of Katushka fluorescent protein (KFP), and a rabbit beta-globin polyadenylation signal. The Katushka expression is driven by the CAG promoter upon Cre recombinase-mediated excision of the floxed STOP cassette. Five founder mice were generated, three of which transmitted germline. Two lines 3 and 13 which contained a single integration event, were further expanded and characterized. No significant differences were observed between them. Most of the studies were performed with line 3. (J:167974)