library_construction_protocol: For immunoprecipitation, the supernatant was incubated overnight at 4°C with 5 μg SF3B6 antibody (thermo: PA5-57077) and control IgG-antibody (AC005). The immunuprecipitates were further incubated with protein A/G Dynabeads (Thermo Scientific) for 2h at 4°C. After applying to magnet and removing the supernatants, the beads were sequentially washed with lysis buffer (1× PBS, 0.1% SDS, 0.5% NP-40 and 0.5% sodium deoxycholate) and high-salt buffer (250 mM Tris 7.4, 750 mM NaCl, 10 mM EDTA, 0.1% SDS, 0.5% NP-40 and 0.5 deoxycholate), respectively. Resuspend the beads in of Elution buffer (50 mM Tris 8.0, 10 mM EDTA and 1% SDS). The RNA was purified with Phenol: chloroform: isopentyl alcohol (25:24:1 pH<5) reagent (Solarbio). The cDNA libraries were prepared with the KAPA RNA Hyper Prep Kit (KAPA, KK8544) according the manufacturer's procedure.