Answer:
Proto-oncogenes stimulate normal cell growth and division and tumor suppressor genes prevent uncontrolled growth
Step-by-step explanation:
Both gene types play a role in cancer development.
Proto-oncogenes are genes responsible for the control of normal cell growth. They encode for proteins that induce growth and proliferation of the cell. When mutation occurs, proto-oncogenes become oncogenes and contribute to the development of cancer. As a consequence, the cell cannot control its growth.
On the other hand, tumor supressor genes normally have repressive effect on the cell growth (promote cell death-apoptosis). When a mutation in this gene occurs, this gene loses its function an that also leads to uncontrolled cell proliferation.