Bioluminescence imaging of Luc⁺ MM.1S cells injected intravenously into the tail veins of SCID/NOD mice. Cells were incubated in vitro before injection in 50 μM AMD3100 or control PBS for 4 hours at 37°C. Whole body real-time bioluminescence imaging was performed every 5 minutes for 90 minutes after injection. (A) Equal distribution of bioluminescence in the control (CTRL) and treated (AMD3100) mice 5 minutes after injection. (B) Thirty minutes after injection, fluorescence intensity diminished in the cardiopulmonary area, indicating exit from the circulation in the CTRL mice. In AMD3100-treated mice, bioluminescence remained high in the cardiopulmonary area.