Question: what makes a cell to reproduce another cell in the body ?

Alexis Barr answered on 16 Jun 2013:

This is an excellent question and one we are still trying to understand the answer to. We know part of what makes a cell reproduce. There are chemicals known as Growth Factors that are produced by cells. These bind to the surface of cells and send a chemical signal into the cell to instruct the cell to start reproducing. When Growth Factors are not there, the cell should stop reproducing. One of the problem in cancer is that cancer cells no longer need Growth Factors to reproduce – they can just keep reproducing over and over again with no signal. Because of this, a tumour forms which is a lump of cells reproducing out of control.