GATA-3 (GATA binding protein 3) is a member of the GATA family of transcription factors. This 50kDa nuclear protein regulates the development and subsequent maintenance of various human tissues, including hematopoietic cells, skin, kidney, mammary gland, and the central nervous system. Among several other roles, GATA-3 is involved in luminal cell differentiation in the mammary gland and appears to control a set of genes involved in the differentiation and proliferation of breast cancer. The expression of GATA-3 is associated with the expression of estrogen receptor-alpha (ER) in breast cancer. GATA-3 is a novel marker for bladder cancer. The study demonstrated that GATA-3 stained 67% of urothelial Carcinomas but none of the prostate or renal carcinomas.