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