We validated the RNA‐seq results by conducting qRT‐PCR analyses on two HNSCC cell lines, which demonstrated that squamocin significantly upregulated a set of key UPS genes including E1s (UBA6), E2s (UBE2Z, UBE2B, UBE2E2, UBE2E3 and UBE2S), and E3s (FBXW7) (Figure S6A, Supporting Information). This evidence concerns the gene UBE2E2 and head and neck squamous cell carcinoma.