he nuclear receptor corepressor SMRT is a broad specificity corepressor for many members of the nuclear receptor superfamily, in addition to numerous other classes of transcriptional factors. SMRT is broadly expressed in a variety of tissues, with particularly high levels in the central nervous system (olfactory bulb, cerebellum, hypothalamus), reproductive systems (testis, uterus, ovary), aorta, thymus and white adipose tissue. SMRT has been shown to be upregulated in malignant endometrium. Null deletion of SMRT is embryonic lethal due to a heart defect. Targeted deletion of SMRT demonstrated its critical role in forebrain development and in the maintenance of the neural stem cell fate.