{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"GATA3 (GATA-binding protein 3) is a transcription factor that belongs to the GATA family of zinc finger proteins, which helps regulate the development of T lymphocytes, mammary epithelial cells, and urothelial cells. GATA3 is critical for the development of T cell precursors in the thymus and the differentiation of T cells into Th2 cells, thus detection of GATA3 in tumors of the thymus may identify thymic epithelial cells. GATA3 is essential for the development and maintenance of mammary epithelial cells epithelial cell identity and is expressed in normal and neoplastic breast tissue. Loss of GATA3 has been associated with a subset of breast cancers, particularly estrogen receptor-positive (ER+) and luminal subtype tumors. Detection of GATA3 may also distinguish urothelial cells in various bladder cancers."}]}]}