To assess whether SMYD3 affects the global levels of H3K4me3 in HPV-negative HNSCC cells, Western blotting for H3K4me3 was conducted in HN-6 cells after 6 days of treatment with SMYD3 targeting siRNAs (Supplementary Fig. 4A). Here, SMYD3 is linked to head and neck squamous cell carcinoma.