NGF/TrkA signals can also be detected in axons and dendrites via Rab7 (late endosome) and Rab11 (circulating endosome) . In comparison, newly produced NGF/TrkA endosomes is Rab5-positive during the early phases of retrograde transport. They develope and change into Rab7-positive late endosomes nearby . Retrograde transport is directed toward the soma of neuron. However, it is delayed in neurons due to the great distance traveled by axons. Endosomes positive for Rab5 and Rab7 represent a parallel transport mechanism for NGF/TrkA. Continuous signal transduction is carried out by Rab5-positive endosomes, whereas degradation and down-regulation are carried out by Rab7-positive endosomes . The acidic environment of Rab7-positive late endosomes may result in the dissociation of NGF and TrkA. The activity renders them unsuitable for signaling endosome .