hSIN3B interacts with ETO homologues, but not with AML1-ETO. COS-7 cells were transfected with ETO (E), MTGR1 (R), MTG16 (16) or AML1-ETO (AE) in combination with hSIN3B (S). Cell lysates were analyzed by IP-Western, as described in Materials and Methods. IP and Western were performed with α-E (ETO specific), α-R (MTGR1 specific), α-16 (MTG16 specific) and α-S (hSIN3B specific). (A-C) ETO and MTG16 co-precipitated hSIN3B (lane 2 of A and C). Reciprocal experiments showed that hSIN3B co-precipitated ETO and MTG16 (lane 5 of A; lane 6 of C). MTGR1 did not co-precipitate hSIN3B or vice-a-versa (lanes 2 and 5 of B). Arrowheads show the position of hSIN3B corresponding to approximately 135 kDa and ETO corresponding to approximately 75 kDa (lanes 2 and 4). (D) AML1-ETO failed to co-precipitate hSIN3B (lane 2). The reciprocal experiment with the same lysates showed that hSIN3B did not precipitate AML1-ETO (lane 5). The size of AML1-ETO is about 100 kDa. (E) Control experiments showed that none of the antibodies bound unspecifically. Lower panel shows the input of hSIN3B and ETO homologue in 2% of IP lysate. The positions of the molecular weight markers are indicated at the left.