Nuclear receptors Nur77 , NURR1 and NOR -1 belong to the family of Nur77 and the steroid receptor superfamily - thyroid . These proteins are involved in the processes of thymocyte apoptosis , differentiation of nerve cells , the production of steroid hormones. Influence on these processes for therapeutic purposes requires the knowledge of mechanisms of regulation of expression and function of Nur77 family proteins and their role in various signaling pathways . Nur77 expression and function is regulated at the level of gene transcription and protein phosphorylation . Nur77 family proteins function as transcriptional activators in the form of monomers , homodimers and heterodimers with retinoid X receptors type . Nur77 family proteins function in crossing signaling pathways dependent on receptors for growth factors , hormones , antigens ( T cell receptor ) signaling pathways controlled by glucocorticoids and derivatives of vitamin A. In the signaling pathway leading to apoptosis Nur77 is exported from the nucleus to mitochondria and acts as an adapter protein .