Effect of tumour necrosis factor (TNF)-α and confluence on discontinuous adherens junctions, stress fibres and focal adhesions. Confluent unstimulated human umbilical vein endothelial cells (HUVECs) (A), or HUVECs stimulated with 10 ng/ml TNF-α for 20 h (B) in growth medium, were scratched with a plastic tip and after 5 h cells were fixed and stained for actin filament, paxillin and β-catenin. All images are projections of z-stacks of confocal images. Left images show a general view of five confocal fields sequentially acquired and superimposed from the scratch edge (top) into the confluent monolayer (bottom). Black lines on left indicate the edges of each confocal field. Right panels show the boxed areas at higher magnification, either at the scratch edge (1 and 3) or within the confluent monolayer (2 and 4). Arrowheads show stress fibre tips associated to paxillin clusters, empty arrowheads points to the tips of the same stress fibres associated to discontinuous junctions on the other side.