To explore the function of TRIM21 in NPC, we generated a stable TRIM21 gain-of-function (GOF) NPC cell line, and TRIM21 CRISPR (clustered regularly interspaced short palindromic repeats) knockout mutant (loss of function, LOF) NPC cells (Additional file 1: Figure S1a). This evidence concerns the gene TRIM21 and nasopharyngeal carcinoma.