sentence: Proneurotrophins , such as pro-nerve growth factor ( proNGF ) and pro-brain-derived neurotropic factor ( proBDNF ) , can trigger neuronal apoptosis , growth cone retraction , and regulate neuronal plasticity by forming a ternary complex with VPS10p members SorCS2 or Sortilin and the p75 neurotrophic receptor ( p75NTR ) .