Optical micrograph showing immunofluorescene of the actin cytoskeleton of a human bone cancer cell. The cytoskeleton, shown in green, is responsible for the generation adhesions, which control the interaction of the actin. Cytoskeletons with the environment outside the cell are shown in red. Finally, the blue dots reveal collagen which provides an anchor for teh focal adhesions. Tension generated through these attachments drives the formation of bundles within the actin cytoskeleton. By controlling the placement of the collagen in this pattern, we can study how constraining the size of individual focal adhesions regulates the tension-dependent structures of the actin cytoskeleton.