SULF2 and head and neck squamous cell carcinoma: In our univariate model, the association of SULF2 protein with PFI of HNSCC patients shows the same trend as SULF2 mRNA; patients with tumor positive for SULF2 protein showed worse clinical outcomes than patients with negative SULF2 but the difference does not reach statistical significance (HR = 1.630, p = 0.199, Figure 2C) which is likely due to the small sample size and semi-quantitative nature of the IHC measurement.