CDKN2A and cervical intraepithelial neoplasia: A meta-analysis of 61 published articles on p16 immunohistochemical staining showed that p16 exhibited diffuse positive staining in 2% of normal cervical squamous epithelium, 38% of low-grade cervical intraepithelial neoplasia (CIN1), 62% of CIN2 and 82% of CIN33.