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Colon cancer. Coloured scanning electron micrograph (SEM) of a freeze-fractured plane through the mucosal surface of a cancerous colon. The surface of the colon (grey) is irregular, with an abnormal bumpy appearance caused by chaotic cell growth. The fracture plane (centre and lower frame) shows the thickened and rough layers of surface cells (blue and orange-brown). Both aspects are typical of the malignant, uncontrolled growth that is cancer. Colon cancer is one of the most common cancers in the developed world. Symptoms include faecal blood, constipation or diarrhoea, and abdominal pain. Treatment involves surgery and chemotherapy. Magnification unknown. (KEYSTONE/SCIENCE PHOTO LIBRARY/STEVE GSCHMEISSNER)