Figure 5: Overview (a) and magnification (b) of a FIB cross-section of a HepG2 cell cultured for 24 h on a nanoporous alumina membrane with pore diameters of  nm. Inset in (a) shows the penetration of filopodia into the pores of the membrane. Inset in (b) shows a magnification of cellular protrusions extending into the pores from the cell bottom (indicated by arrows) [34].