RU486: The Abortion Pill
Many diseases are caused by over- or underproduction of protein. Overproduction of a protein that blocks the attachment of an activator can result in a decreased ability for it to attach to an enhancer or coactivator. Underproduction can result in a stabilization of the transcription basal machinery.
The protein RU486 (the "abortion pill", also known as Mifepristone) represses the function of certain steroid receptors (protein) which are activators of embryogenesis.