No significant difference in the radioactivity levels in the A431-CCK2R(+) tumours was observed between kit and wet-labelling animal groups (9.24 ± 1.35%ID/g and 8.49 ± 0.39%ID/g, respectively; P > 0.05), or between untreated and gelofusine-treated mice (9.24 ± 1.35%ID/g and 7.99 ± 2.45%ID/g, respectively; P > 0.05). The gene discussed is CCKBR; the disease is neoplasm.