RFP-Puro Reporter Cell Line-A549 is a polyclonal population which is constructed by lentivirus transduction, followed by stable cell selection. This cell line stably expresses RFP and puromycin driven by the spleen focus-forming virus (SFFV) promoter. It is an ideal positive control for use in fluorescence assays. In addition, A549 cells can form tumors in mouse lungs. The in vivo growth of these tumors can be monitored using optical imaging.