To investigate the effects of USP21 on nasopharyngeal carcinoma cell proliferation, two kinds of nasopharyngeal carcinoma cells (C666-1 and 5-8F) were transfected with shRNA control (sh-NC) and two kinds of USP21-targeting shRNA (sh-USP21#1 and sh-USP21#2) to ensure long-term transfection efficiency, respectively. Here, USP21 is linked to nasopharyngeal carcinoma.