Genes which can potentially induce neoplastic transformation. They include genes for growth factors, growth factor receptors, protein kinases, signal transducers, nuclear phosphoproteins, and transcription factors. When these genes are constitutively expressed after structural and/or regulatory changes, uncontrolled cell proliferation may result. Viral oncogenes have prefix "v-" before the gene symbol; cellular oncogenes (proto-oncogenes) have the prefix "c-" before the gene symbol.