ABSTRACT
Considerable evidence has been obtained in recent years to support the hypothesis that cancer is the result of alterations in particular cellular genes. These altered genes can function in either a dominant or recessive fashion to allow cancer cells to evade the controls under which the growth of normal cells is tightly regulated. Genes that act in a dominant fashion are called oncogenes, and those that act in a recessive fashion are called tumor suppressor genes. Acutely transforming retroviruses are the result of rare recombination events between replication-competent retroviruses and cellular genes. The life cycles of retroviruses have been extensively studied, and general details are known. The newly acquired genetic information is often fused to viral coding sequences, and additional alterations in the viral oncogene are often found when compared to the cellular proto-oncogene. Thus, the molecular details of the evolution of the acutely transforming retrovirus from its precursors can be determined by a detailed examination of these genetic differences.
