In the present study, we found that formation of TR3/RXRalpha heterodimers in the nucleus and their subsequent translocation into the cytoplasm, in association with regulation of apoptosis-related proteins Bcl-2, Bcl-xl and Bax, was critical for apoptosis induction by ATRA in breast cancer cells MCF-7.     ///    "In ATRA-induced MCF-7 cells, highly expressed TR3 favours the formation of TR3/RXRalpha and promotes the TR3/RXRalpha signalling pathway causing apoptosis. "