The phosphorylation of MRLC is not associated with the axonal diameter. (a) In DIV14 rat hippocampal neurons, endogenous periodic axonal actin rings were labeled using SiR-actin, followed by staining using diphosphorylated MRLC antibody (p-MRLC). Boxed regions are amplified in the bottom panels. Scale bars = 5 µm. (b) Pearson’s correlation coefficient (r) was calculated between the local p-MRLC level and the axon diameter. n values are labeled on the panels, representing numbers of axonal segments analyzed. Values were measured from axons of three independent cultures.