At protein level both, percentage of cells (p = 0.04) (Supplementary Figure S1 A) and staining intensity of KLF4 (p = 0.025) (N = 58; HPV-negative: 45, HPV-positive: 13) were higher in HPV-positive than in HPV-negative primary HNSCC (Fig. 2 C). The gene discussed is KLF4; the disease is head and neck squamous cell carcinoma.