To explore the mechanisms by which PRMT5 may regulate the development of head and neck tumor, we first analysed differential gene expression in samples with differential PRMT5 expression using TCGA HNSC samples, and in total we identified a large number of PRMT5-regulated genes, including DDX21, S100A8, SMC4 (Figure 3A). This evidence concerns the gene DDX21 and head and neck neoplasm.