Fluorescent micrograph showing human osteosarcoma cells grown in culture. Osteosarcoma is the most common form of bone cancer and occurs due to an error in the growth of osteoblast cells, the cells that are responsible for generating new bone tissue. In this image the microtubules are stained in red and the cell nucleus has been stained in blue (DAPI). Microtubules are an important component of the cell’s cytoskeleton, composed of a single type of protein, called tubulin, microtubules function to determine cell shape and are dynamic structures involved in a variety of cell movements.