Figure 3.

Cytoskeletal characterization during channel invasion reveals hallmarks of mesenchymal and amoeboid invasion. (A) Bleb structures are observed in phase contrast in all four permeative cell lines upon channel exit. Scale bars = 10 μm. (B) Immunofluorescence staining in fixed cells reveals punctate focal adhesions in cells transiting 10 μm channels (left), but a loss of paxillin expression and organization in cells transiting 3 μm channels (right). Scale bars = 10 μm. (C, D) Maximum intensity projections of laser scanning confocal image stacks of fixed cells in 10 and 3 μm channels. Strong F-actin is evident in 10 μm channels, while 3 μm channels display bleb structures at the forward and rear ends of the cell and little perinuclear actin expression. Scale bars = 3 μm. (E) Individual slices through the height of the channel show diverse blebs at the leading edge. Scale bars = 3 μm.