Evidence also suggests that PI3K/Akt is activated downstream of Gastrin-Releasing Peptide (GRP)/Gastrin-Releasing Peptide Receptor (GRPR) and Brain-derived neurotrophic factor (BDNF)/TrkB signaling, which are reported to be overexpressed in human neuroblastoma (151, 153, 156). Here, GRPR is linked to neuroblastoma.