Oncogenes are specific genes that have the potential to cause cancer when they are mutated or expressed at high levels. Normally, these genes help regulate cell growth and division, but when they become altered, they can lead to uncontrolled cell proliferation, contributing to tumor formation. These genes often encode proteins that are involved in signaling pathways, which control various cellular functions. Examples of oncogenes include Ras, Myc, and HER2. Understanding oncogenes is crucial for developing targeted cancer therapies that can inhibit their activity and slow down or stop tumor growth.