NPM_S-RAR forms heterodimers with RXR. (A) In vitro translated ³⁵S-RXR was incubated with MBP or MBP-NPM_S-RAR protein. Complexes were purified over amylose resin and analyzed on 8% SDS-PAGE. (B) ³⁵S-RXR was preincubated with in vitro translated NPM_S-RAR or control reticulocyte lysate before addition of anti-RAR antibody. Complexes were precipitated with Protein A-sepharose and analyzed on 8% SDS-PAGE. (C) ³⁵S-NPM_S-RAR was preincubated with in vitro translated RXR or control reticulocyte lysate before addition of anti-RXR antibody. Complexes were precipitated with Protein A-sepharose and analyzed on 8% SDS-PAGE.