A brief explanation of the proteins in the body that regulate cell growth is also helpful in understanding cancer cells. Our DNA carries genes that in turn are the blueprint for proteins produced in the body. Some of these proteins are growth factors, chemicals that tell cells to divide and grow. Other proteins work to suppress growth. Mutations in particular genes (for example those caused by tobacco smoke, radiation, ultraviolet radiation, and other carcinogens) can result in the abnormal production of proteins. Too many may be produced, or not enough, or it could be that the proteins are abnormal and function differently.
Cancer is a complex disease, and it is usually a combination of these abnormalities that lead to a cancerous cell, rather than a single mutation or protein abnormality.