EGFR and breast cancer: For example, the epidermal growth factor receptor (EGFR) and other growth factor receptor genes are mutated or overexpressed in various cancers, the KRAS gene is often deregulated (close to 95%) mutated in pancreatic cancers, the PIK3CA (PI3K) gene is frequently disrupted in certain types of breast cancer (hormone-responsive breast cancers), and the PTEN gene, a tumor suppressor protein is mutated in various cancers.