SRC-1 is a transcriptional coregulator which mediates the activating functions of members of nuclear receptor superfamily. SRC-1 is the prototypical member of the SRC/p160 coactivator family. SRC-1 is broadly expressed in a variety of tissues, with particularly high levels in several areas of the brain (cerebrum, corpus striatum, cerebellum, hypothalamus) in addition to the thymus, testis, pituitary and white adipose tissue. SRC-1 overexpression has been documented in breast cancer, endometrial cancer and prostate cancer. Loss of SRC-1 expression results in defects in skeletal and reproductive function, in addition to dysfunction in other physiological systems.