PIK3CA and cancer: Some of the key genes often mutated in HPV-associated cancers are in PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha), PTEN (phosphatase and tensin homologue), HLA-A and HLA-B (human leukocyte antigen A and B), TGFβ (transforming growth factor beta), and components of the NOTCH1 and RAS/EGFR/ERK pathways; in contrast mutations are very rarely found in p53 and pRB [13,21].