PIK3CA and gastric cancer: Specifically, PIK3CA, which encodes for the catalytic subunit p110α of class IA PI3-kinase, is amplified and overexpressed in ovarian cancer [18] and is commonly gain-of-function mutations in colon [19], brain [20], breast [21] and gastric cancers [22–25], but PIK3CA mutations seem to have a limited impact on growth of melanoma, up to now [26].