Although STAT3 is constitutively active in numerous types of cancers including breast cancer, skin cancer, ovarian cancer, prostate cancer, multiple myeloma, lymphomas and leukemia, brain tumor, Ewing sarcoma, gastric cancer, esophageal cancer, colon cancer and pancreatic cancer, one report showing STAT3 mutation in the SH2 domain in large granular lymphocytic leukemia, resulting in an increased activity of the protein [112]. The gene discussed is STAT3; the disease is breast cancer.