Additionally, bioinformatics analyses by Henderson et al. revealed that the proto-oncogene, PIK3CA, was frequently mutated in tumor types expressing high APOBEC mRNA levels such as HPV-positive CESC and HNSCC (cervical squamous cell carcinoma and endocervical adenocarcinoma and head and neck squamous cell carcinoma) [125]. This evidence concerns the gene PIK3CA and head and neck squamous cell carcinoma.