Our collaboration with the lab of Jim Salzer (NYU) is just out. We visualized the association of phospho-myosin light chain (pMLC, an activator of the contractile myosin-II) with actin rings along the axon initial segment (AIS). This was done using two-color STORM. Moreover, acute treatment with KCL (mimicking elevated activity) resulted in a disappearance of the phospho-MLC signal before the disorganization of the actin rings. This suggests that myosin-II contractility has a role in setting the AIS shape and position along the axon, and that release of this contractility could be a key remodelling step for the activity-dependant plasticity of the AIS.