To study how C3a regulates Sox‐2, we investigated the role of the Wnt/β‐catenin pathway in the self‐renewal of stem‐like cells showed in head and neck squamous cell carcinoma.25 C3aR expression was knocked down by C3aR siRNA transfection (Figure 4A,B). The gene discussed is C3AR1; the disease is head and neck squamous cell carcinoma.