Oncogene
"The term oncogene was introduced in the middle of the 1960s to denote special parts of the genetic material of certain viruses. It was believed that this part of the genetic material could direct the transformation of a normal cell into a tumor cell... The favourite theory of the time was that virus-mediated cell-to-cell transmittance of oncogenes was the origin of all forms of cancer. This view was later proven to be incorrect".