HEK293 cells were cultured and stimulated as described above and lysed. Proteins complex (300 μg) immunoprecipitated with HuB antibody or IgG were subjected to SDS-PGAE and then in-gel protein digestion and peptides recovery conducted by Beijing Protein Inovation Co., Ltd. The solutions containing peptides released during in-gel digestion were measured using Nanoflow UPLC (Easy-nLC 1200 system, Thermo, Cambridge, MA, USA) coupled to Mass Spectrometer (Q Exactive™ Hybrid Quadrupole-Orbitrap™, Thermo).