The tumour uptake in A431-CCK2R xenografts was remarkably high, with values of 68.1 ± 10.0% IA/g for the first time point of 1 h p.i. studied and dropped to 28.9 ± 7.2% and 12.6 ± 3.3% IA/g 1 and 3 days after injection, respectively. The gene discussed is CCKBR; the disease is neoplasm.