As shown in Figure 4E and Figure S2E, the expression of major regulators of G1-S checkpoint (cyclin D1, cyclin-dependent kinases (CDK4 and CDK6)) was downregulated in CAL-27 and FaDu cells with SQLE knockdown, while SQLE upregulation in SCC-9 and SCC-25 cells had opposite effect, demonstrating function of SQLE in promoting cell cycle progression in HNSCC cells. The gene discussed is CDK4; the disease is head and neck squamous cell carcinoma.