However, sequence analysis results indicate the absence of qualified sites on mRNA, and the existence of ac4C modification in eukaryotic cell mRNA remains a subject of contention.10,26 Since NAT10 is well-known for its catalyzing the formation of ac4C on tRNASer and tRNALeu,10,27,28 we then analyzed ac4C on tRNA in HNSCC cells. This evidence concerns the gene NAT10 and head and neck squamous cell carcinoma.