PIK3CA mutations are common in multiple human cancers.17 These mutations produce a constitutively active form of the PI3K protein, which results in the phosphorylation of multiple downstream targets responsible for a wide variety of vital cellular functions.18, 19 PI3K initiates this signaling pathway through the phosphorylation of phosphatidylinositol 4,5-bisphosphate to phosphatidylinositol 3,4,5-triphosphate. Here, PIK3CA is linked to cancer.