Traction on immobilized netrin-1 is sufficient to reorient axons.

During embryonic development, axons are guided to their target by patterning proteins encountered along their trajectory. These cues can be linked to the cells that produce them or secreted into the extracellular matrix. Whether secreted cues, like netrin-1, provide traction for the growth cone when they become attached to the extracellular matrix is unclear. Advancing spinal commissural neuron growth cones were shown to generate local forces of 4 to 15 piconewtons but, when confronted with immobilized netrin-1, generated traction forces in excess of 63 piconewtons on netrin-1 that can redirect the trajectory of the axon.