Cancer cells. Colored scanning electron micrograph (SEM) of cancer cells (gray) which have just undergone division. Two lymphocyte (yellow) blood cells are seen in close proximity. The two cancer cells have a typically uneven surface with cytoplasmic projections which may be used for movement. Cancerous (malignant) cells divide rapidly and possess the ability to invade and destroy surrounding tissues and travel to distant parts of the body. Lymphocytes occur at these sites as an immune response. They are white blood cells which may serve as natural killer cells attacking both foreign invaders and destructive cancers. Magnification: unknown.