Plays a major role in early metanephros and genital development. Expressed in the inner ear, with a high presence in the spiral ganglia, cochlear nerve bundles, and hair cells. At 15.5 dpc, expressed in kidney, ureter and bladder (PubMed:29100090). At 16.0 dpc, strong expression in the liver, thymus, intestine, kidney, and brain. In the brain, high levels in the ventricular zone and in the neopallial cortex. In the kidney, highest levels in the nephrogenic zone located in the cortical region of the kidney. Also observed in epithelial cells of the differentiating renal tubules. At P0, strong expression in the nephrogenic zone (PubMed:29100091). In the inner ear, prominent expression is observed between 13 and 16 dpc (PubMed:29955957). Embryonic lethal at the homozygous state. At 13.5 dpc, all homozygous embryos are significantly smaller compared to wild-type and heterozygous littermates and present with exencephaly. Male and female embryos lack kidney and show absence of Wolffian and Muellerian ducts, respectively. However, mesonephric tubules are consistently observed. Some potential remnants of ureteric bud are present in most mutant embryos. In male mutant embryos, the gonads are severely affected, being small and with poorly organized sex-cords compared to wild-type littermates. Mutant embryos also show cardiac morphogenesis defects with superimposed ventricles. Belongs to the GREB1 family.