Growth Regulation By Estrogen In Breast Cancer 1 (GREB1)

GREB1 is an estrogen-responsive gene that is an early response gene in the estrogen receptor-regulated pathway. It is thought to play an important role in hormone-responsive tissues and cancer. Three alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.The deduced GREB1a, GREB1b, and GREB1c isoforms contain 1,949, 457, and 409 amino acids, respectively, and share a large central region and contain diverging 3-prime ends. GREB1b shares amino acids 1-449 with GREB1a, while GREB1c and GREB1a share identical amino acids 1-386. RT-PCR analysis detected GREB1 expression in ER (ESR1)-positive breast tumors with 3.5-fold higher expression in ER-positive compared with ER-negative breast tumors.