UBE2E3 and head and neck squamous cell carcinoma: 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).