Figure 1.

Scanning electron microscopy (SEM) images showing a focused ion beam (FIB) cross sections of a cell cultured on an array of 2 μm diameter pillars. The samples were fixed and stained following a recently developed ROTO protocol (see S2 for more details) and embedded in a thin film of epoxy resin. The cell membrane (indicated by red arrows) can assume a “tentlike” configuration (a) or be tightly wrapped around the pillars (b). (c) Adhesion-induced mechanism of permeabilization. (d) Traction-induced mechanism of permeabilization. Inset: the membrane’s bending is dictated by the local radius of curvature rather than by the micropillar/nanopillar diameter.