4T1 cells engineered to express GFP and luciferase (4T1-GFP-luciferase) were injected into the tail veins ofEfna1+/+,Efna1+/-, andEfna1-/- littermates.In vivo bioluminescence imaging several hours after injection illustrated comparable signal across all mice (Figure 2A, B), indicating ephrin-A1 host deficiency did not impact tumor cell trafficking and lodging within the lung, at least in this short time frame. The gene discussed is EFNA1; the disease is neoplasm.