The c-src gene in animals is turned on during periods of cell growth and division. The Rous sarcoma virus genome contains a mutated form of this gene, v-src, which produces a protein that is always activated. Infections of chickens with this virus cause cancers to develop. What type of gene is c-src?

proto-oncogene

Explanation:

There are many genes whose products are involved in cell growth and differentiation process. These genes when mutated can be over expressed due to which the cells can proliferate indefinitely. Such genes are called as proto-oncogenes. They do not normally cause cancer but their mutation can lead to cancer. Examples of proto-oncogenes are TRK, MYC, ERK etc.

Here c-src gene is normally involved in cell division process. Its mutated form v-src produces a protein which is always in activated state. As a result uncontrolled cell division occurs and cancer is observed in cells having v-src instead of c-src. Hence c-src is a proto-oncogene.