CDKN2A and cervical squamous intraepithelial neoplasia: The use of p16 helps to distinguish CIN3 from its imitations, such as immature squamous metaplasia or therapeutic changes [25], but its sensitivity in detecting CIN2/CIN3 may be reduced by a small fraction of CIN 2/3 or carcinomas that may show weak or negative p16 staining [26].