Figure 5: A workflow summary of the study. The study was done in 3 steps; Step1) isolated the SMN complexes from the high salt nuclear extract and identified FOP as a component of the SMN complexes, Step 2) isolated a novel FOP-SMN complexes reciprocally using HB-FOP as affinity bait, and identified their components by LC-MS/MS-Mascot analysis, and Step 3) quantified the changes of the components of the endogenous nuclear SMN complexes before and after knockdown of FOP by SILAC-LC-MS/MS method.