Moreover, CIN tumors are distinguished by the accumulation of mutations in specific oncogenes and tumor suppressor genes [e.g., APC, KRAS, phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA), B-Raf proto-oncogene, serine/threonine kinase (BRAF), SMAD4, and TP53], thereby activating pathways critical for carcinogenesis. Here, PIK3CA is linked to cervical squamous intraepithelial neoplasia.