To assess whether depletion of SUV420H1 affects the proliferation of HPV-negative HNSCC cells, we utilized three different siRNAs targeting SUV420H1, but not other H4K20 methyltransferases, such as SUV420H2 and SETD8 (Supplementary Fig. 4). The gene discussed is KMT5B; the disease is head and neck squamous cell carcinoma.