HeLa cervical cancer cells. Fluorescence light micrograph of HeLa cervical cancer cells stained for the cytoskeletal proteins actin (red) and tubulin (green), and for nuclear DNA (blue). Cancer cells spread in the body with the help of mutated genes that drive changes in the cytoskeleton of the cells, the protein filaments and microtubules that control cell shape and contribute to cell movement. Study of the mechanisms by which cancer cells move through the body may lead to targeted therapies that reverse these processes. HeLa cells are a continuously cultured cell line of human cancer cells. They are immortal and so thrive in the laboratory. HeLa cells are widely used in biological and medical research.