PIK3CA and cancer: PIK3CA, the gene coding for the catalytic subunit p110α of PI3K, is one of the most commonly mutated oncogenes in multiple human malignancies (3441 mutated samples among a total of 27725 samples, about 12%, according to the Catalogue of Somatic Mutations in Cancer (COSMIC) Database (http://www.sanger.ac.uk/genetics/CGP/cosmic/)).