BDNF and neuroblastoma: As we have reported that the PI3K/Akt signal transduction pathway mediated the BDNF/TrkB-induced chemo-resistance in NB [9–11], and this study showed that the PI3K pathway also mediated the BDNF/TrkB-increased migration and invasion, we further studied whether or not Akt and its downstream targets mTOR were involved in BDNF/TrkB-induced increases of cell migration and invasion.