Limitation of substratum size alters cytoskeletal organization and behaviour of Swiss 3T3 fibroblasts.

Cell spreading and adhesion formation in Swiss 3T3 cells was studied on circular adhesive islands of size 400-500 microns 2 made by evaporating palladium through a mask onto an underlying non-adhesive surface. Cell spreading was limited since focal contacts were restricted to the palladium. On islands less than 2000 microns 2, focal contacts and actin bundles were arranged at the cell periphery. On islands less than 1000 microns 2, the size and number of focal contacts were reduced. Focal contacts may be important regulators of proliferation, but they do not seem to form a deterministic link between substratum contact and proliferative stimulus.