RiboTag IP was performed as described in the section on Immunoprecipitation. After IP, all samples were used for RNA extraction using the RNeasy Plus Micro kit (Qiagen, 74034). RNA purity and quantification were evaluated using the NanoDrop 2000 spectrophotometer (Thermo Scientific, USA). RNA integrity was assessed using the Agilent 2100 Bioanalyzer (Agilent Technologies, Santa Clara, CA, USA). RNA samples were transferred to the OE Biotech Co., Ltd. (Shanghai, China) for cDNA library preparation using NEBNext Ultra II Directional RNA Library Prep Kit according to the manufacturers instructions. Samples were sequenced using the illumina Novaseq6000 platform.