The invention is based on the elucidation of a mechanism by which HPV promotes oncogenesis and provides a methods of diagnosing malignant tumors and methods of preventing the development of malignancies or inhibiting tumor growth. A method for diagnosing a neoplasm in a mammal is carried out by measuring the level of helicase-like transcription factor (HLTF) in tissue of the mammal. An increase in the level of HLTF in the tissue compared to the level in a normal control tissue indicates the presence of a neoplasm in the tissue.