CDKN2A and neoplasm: However, no conclusions on the applicability of p16INK4a in conjunctival CIN and SCC can be taken due to the broad variability in the definition of p16INK4a overexpression (percentage of tumor cells or binary definition (positive/negative), nuclear and/or cytoplasmatic staining), the immunohistochemistry staining probes used, HPV results, and HPV detection modalities used (PCR-based (HPV DNA PCR, HPV RNA RT-PCR) and/or in-situ hybridization (ISH)-based (HPV DNA ISH, HPV RNA ISH) or combination of techniques).