p16

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

Protein expressed by p16-INK4a tumor suppressor gene important in cell cycle regulation. Overexpression is associated with viral oncogenes E6 and E7 and therefore a surrogate marker for high-risk types of human papilloma virus (HPV) in cervical, vulvar, vaginal, and anal mucosa. Overexpression in squamous cell carcinomas of the head and neck can serve as a prognostic marker.