The CAG promoter was used to drive expression of a fusion protein composed of monomeric Kusabira-orange (mKO2) and the sequence encoding amino acid residues 30-120 of human CDT1. mKO2 is a modified monomeric form of a fluorescent protein derived from Fungia concinna (a species of coral.) The transgene causes red fluorescence in cells at the G1 stage of the cell cycle. Sixteen lines were identified. (J:146883)