RFP Reporter Cell Line-CT26 is a polyclonal population which is constructed by lentivirus transduction, followed by stable cell selection. This cell line stably expresses RFP and neomycin resistance gene driven by spleen focus-forming virus (SFFV) promoter. It is an ideal positive control for use in fluorescence assays. In addition, CT26 cells can form tumors post implantation into mice. The in vivo growth of these tumors can be monitored using optical imaging for RFP fluorescence.