Definition

A gene that makes one of the proteins in an enzyme called PI3K, which is involved in many important functions in a cell. Mutations (changes) in the PIK3CA gene may cause the PI3K enzyme to become overactive, which may cause cancer cells to grow. PIK3CA gene mutations have been found in many types of cancer, including cancers of the breast, lung, ovary, stomach, brain, colon, and rectum. They have also been found in some genetic conditions.