T22‐GFP‐H6‐FdU injection led to highly selective tumor tissue accumulation (Fig 2B) as measured by fluorescence emission, whereas uptake in CXCR4‐positive (bone marrow or spleen) or CXCR4‐negative (kidney, lung, brain, heart or liver) normal tissues was undetectable, except for a transient accumulation in the liver (Fig 7A), in the same experiment. The gene discussed is CXCR4; the disease is neoplasm.