RT-PCR and western blot analysis confirmed that the expressions of genes and proteins of Groα and the NOD1/2-mediated RIPK2 pathway were higher in late-stage (patient no. 6) than in early-stage (patient no. 5) HNSCC tissues (Figs. 2e and 2f). Here, CXCL1 is linked to head and neck squamous cell carcinoma.