The projection views depict the fluorescence recorded in a migrating primary human epidermal keratinocyte (direction of migration indicated by white arrowhead) showing the distribution of keratin using a pan keratin antibody (A) and filamentous actin using phalloidin (B; merged image in (C)). The nucleus is demarcated in blue by DAPI staining. Side views of the z-planes denoted by broken lines are also shown. A corresponding 3D animation is presented in Supplementary Movie S1. Note that the keratin network is concentrated around the nucleus with lateral extensions of thick KF bundles forming a mustache-like structure (arrows in A) in the rear part of the cell. KF density and bundle thickness decrease toward the cell front. On the other hand, prominent actin stress fibers are seen in the cell rear (arrows in B) and increased actin staining is seen in the lamellipodial-rich cell front. Scale bar: 10 µm.