Some cells in our body, like skin cells, constantly divide to replace skin cells we lose regularly. In terms of wound healing, cells divide to replace the cells lost caused by the wound. Cells communicate with each other with the help of special protein (cyclins), and send signals with each other, just like a switch, when to start and stop dividing. If the wound is already healed, cell dividing will be switched off. If not, cells will continue to divide and form tumor cells.