| In this study , the adopted orphan receptors constitutive androstane receptor ( CAR ) and pregnane 10 receptor ( PXR ) were found to perform direct protein protein interactions with Pit 1 , a representative POU domain factor . ^^^ The ligand dependent interaction profile of Pit 1 with CAR , PXR , and the vitamin D receptor in solution was shown to be that of a corepressor . ^^^ Conversely vitamin D receptor , CAR , and PXR were shown to act as repressors of Pit 1 signaling in different cell lines ( MCF 7 , HaCaT , and GH4C1 ) . ^^^ |