Nuclear receptors are among the most intensively-studied transcription factors.
They are studied because they play fundamental roles regulating cell function and development and also because, as transcriptional switches that can be controlled by small molecules, these proteins are valuable tools for biotechnology. Ecdysone is the steroid hormone that synchronizes insect development and controls the spectacular transformations of metamorphosis. When hormone is not present the dimer interacts with corepressor proteins to inhibit the transcription of nearby genes. When hormone is present the dimer interacts with coactivator proteins to stimulate nearby genes. Many candidate corepressors and coactivators are known but a clear picture has not yet emerged.