4596 Nucleic Acids Research, 2006, Vol. 34, No. 16 (50-UGGAGUUAAGGGAGCAUGGAGTT-30/50-CUCCAU- GCUCCCUUAACUCCATT-30) and DDX47-2 (50-GAUC- CUCAAAGUGAUUCCUCGTT-30/50-CGAGGAAUCACUU- UGAGGAUCTT-30). Luciferase siRNA (28) was used as a control and was kindly provided by Dr H. Nishitani. Isolation of nucleic acids and filter hybridization The siRNA-treated HeLa cells were trypsinized and the cell number was determined using a Coulter counter (Beckman Coulter, Inc. Fullerton, CA). Total RNA was extracted using Trizol reagent as recommended by the supplier (Invitro- gen). Total RNAs from about 4000 cells were electrophoresed in a 1.5% agarose-formaldehyde gel, transferred to a nylon Hybond-N membrane (GE-Healthcare) and cross-linked by UV irradiation. Northern blotting was performed as described previously (29). The DDX47-associated RNAs (Figure 4c) were isolated from FLAG-DDX47-transfected 293 cells and processed as described previously (30). RESULTS Identification of proteins in the NOP132 complex In order to identify proteins that may interact with NOP132 in the cell, we used an anti-FLAG antibody to immunoprecipi- tate NOP132-associated proteins from human 293EBNA cells expressing FLAG-tagged NOP132. Anti-FLAG was used to