Lung cancer cells dividing, coloured scanning electron micrograph (SEM). Lung cancer occurs when abnormal cells divide in a chaotic and uncontrolled manner resulting in the formation of a tumour in the lungs. Lung cancer is the most common cause of cancer death in the UK. In this image the cells are undergoing cytokinesis which is the physical process of cell division which divides the parental cell into two daughter cells. At the end of cytokinesis, the two daughter cells remain connected by the midbody for a short time. The midbody is organised by a set of microtubules and its main function is to localize the site of natural detachment (abscission) between the two daughter cells. The strcuture that accomplishes cytokinesis is the contractile ring which is a dynamic assembly composed of actin and myosin filaments and structural and regulatory proteins. The ring assembles just beneath the plasma membrane and contracts to constrict the cell into two. Magnification: x4000 when printed at 10cm wide.