This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
All are true about neurotrophins except ? 
Select and explain. 
A. Help integrity of postsynaptic neurons, B. TrK B is associated with brain derived neurotrophic factor, C. Helps in growth of cholinergic neurons in basal forebrain, D. Always transpoed antegrade along the axon
D: Always transpoed antegrade along the axon
Answer: D: Always transpoed antegrade along the axon 
Explanation: Ans. is 'd' i.e., Always transpoed antegrade along the axon NeurotrophinsThis name is given to a group of proteins necessary for the survival and growth of neurons.Some of them are synthesized by extraneuronal structures innervated by the neurons, e.g. skeletal muscle innervated by alpha-motor neurons and tissue innervated by autonomic neurons.Many are produced by astrocytes.From the non-neural tissues, neurotrophins are taken up by endocytosis at the nerve terminal and transpoed to the soma by axonal retrograde transpo mechanism.