The cytoskeleton of a cell is a a network of filamentous proteins that extend from the cell's nucleus to the cell membrane. It is composed of a variety of proteins including actin and tubulin.

Image on the left presents a fluorescence microscopic view of an actin inside the cell.Actin is presented as bright yellow, longitudinal structure with few purple ovals inside of it, on a black background.Image on the right presents a fluorescence microscopic view of a tubulin inside the cell.Tubulin is presented as many bright green, star-shaped structures with hundreds of thin, thread-like endings coming from all the sides of it  and with purple-red ovals inside each of the structures.

Figure 1. Actin and tubulin in cells.