Uncontrolled growth
A cell is continuously receiving messages, both from its own genes and from other cells. Some tell it to grow and multiply, others tell it to stop growing and rest, or even to die. If there are enough 'grow' messages, the next stage of the cell's life starts. In a cancer cell, the messages to grow may be altered, or the messages to stop growing or to die may be missing. The cell then begins to grow uncontrollably and divide too often.
