CDKN2A and squamous cell intraepithelial neoplasia: Subsequently, four proteins—topoisomerase II alpha (TOP2A), minichromosome maintenance complex component 2 (MCM2), valosin-containing protein (VCP), and cyclin-dependent kinase inhibitor 2A (p16INK4a)—were quantified in the resulting lysates using enzyme-linked immunosorbent assays, as well as in cervical tumors and squamous intraepithelial lesions (SILs) using immunohistochemistry for further validation.