Cell culture and transfection
293T cells were cultured in DMEM (Gibco, 11965092) supplemented with 10% FBS (TransSerum, FS101-02) at 37 ℃ incubator with 5% CO2. 293T cells were kept in our laboratory. Polyethylenimine (PEI) (Sigma-Aldrich, 9002-98-6) were used to transiently transfect DNA constructs into 293T cells.