KLF4 and cancer: In HPV− HNSCC with irregular p53 coding sequences Slug immunostaining was detected (Figure 4f,h), the CK staining was heterogeneous in the cytoplasm of the tumor cells (Figure 4e,g), KLF4 could be intensive positive or almost completely lost in the cell nuclei of the tumor cells (Figure 4e,g), and vimentin traces could be also present in the cancer cell nests (Figure 4e).