Which choice below shows the correct order in neuronal migration?
1) Binding of new guidance molecules to a neuron, leading edge extension and nucleokinesis.
2) Nucleokinesis, binding of new guidance molecules to a neuron, and trailing end retraction.
3) Trailing end retraction, binding of new guidance molecules to a neuron, and nucleokinesis.
4) Microtubule cage formation around the nucleus, leading edge formation, dissociation of trailing end from adhesion molecules.