Septin 2 is enriched in myelinated axons at paranodes. Immunostaining of rat sciatic for septin 2 and Na+ channels to label nodes (A), PanNF to label nodes and paranodes (B), and Kv1.2 to label juxtaparanodes (C). D, Consistent with septin 2′s reported role in regulating actin dynamics, immunostaining for actin reveals clear colocalization of actin with caspr. other node associated proteins (Na+ channels, caspr, Kv1.2, and βII spectrin). E, Immunostaining of developing rat sciatic nerve for septin 2 and the indicated node-associated proteins. Scale bars, 10 μm; the scale bar in A also applies to the panels shown in B, and C.