Lung cancer cell with blebs, 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. The main cell in the centre of the image is displaying a process known as blebbing. Blebbing (green and red) is a bulge or protrusion of the plasma membrane of the cell which is visible on the cell surface. Blebbing is often seen during programmed cell death (apoptosis) or may be seen when a cell is undergoing physical or chemical stresses. It also has important functions in cellular processes such as cell locomotion, playing a role in cell migration. Magnification: x3000 when printed at 10 cm wide