Confocal light micrograph of cancer cells stained with phalloidin, a fluorescently labelled compound that labels the actin cytoskeleton (cells skeleton). The stress fibres (thickest filaments) keep the cell adhered to the culture dish, while the thinner ones provide structural support to the cytoplasm (cell interior) and are involved in many essential cellular functions. Magnification: x1000 when printed at 10 centimetres wide.