DPP6 and neuroblastoma: Radioactivity signals from the 99mTc-anti-DPP6 nanobody also showed notably high tumor-to-blood (2.9 ± 0.2 and 2.5 ± 0.4 in mice with neuroblastoma and mice with EndoC-ßH1, respectively) and tumor-to-muscle ratios (9.9 ± 3.2 and 9.9 ± 2.2, respectively).