A cassette containing (5' to 3') a splice acceptor, floxed neo/STOP cassette, the coding sequence for Kaposi sarcoma herpesvirus FLICE-inhibitory protein (vFLIP/gp80), and an FRT-flanked IRES-EGFP was inserted into the locus. Cre-mediated recombination is required to achieve expression of the viral protein. (J:172031)