PIK3CA and squamous cell carcinoma: Scanning the mutation patterns through the CC has revealed the presence of non-synonymous somatic nucleotide modifications in diverse genes, such as phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), phosphatase and tensin homolog (PTEN), p53, serine/threonine kinase 11 (STK11), and Kirsten rat sarcoma viral oncogene homolog (KRAS) [46–49], among which PIK3CA- and p53-related modifications have greatly been found in squamous cell carcinomas [50].