BDNF and neuroblastoma: Before our study, BDNF had been shown to play a role in cancer proliferation, invasion and metastasis in central nervous system, due to promote angiogenesis by increasing VEGFR expression through HIF-1α [27].Previous reports of TrkB/BDNF signaling playing a chemoattractant role for development when the early transformation from normal neuroblast to neuroblastoma occurs [28].