KLF4 and head and neck squamous cell carcinoma: To further confirm this relationship in HNSCC, protein levels of Slug (Figure 4A and Figure S2A), Vimentin (Figure 4B and Figure S2A,B) p-p38 (MAPK) (Figure 4C and Figure S2C) as pro EMT factors and KLF4 (Figure 4D and Figure S2D) and E-cadherin (Figure 4E and Figure S2E) as epithelial markers were analysed by Western blotting system in human SCC-25 (HPV−) and UPCI-SCC90 (HPV+) cell lines.