Linear correlation and statistical significance (p < 0.05) between ZEB1 and FSTL1 were observed in cervical cancer (CESC), esophageal cancer (ESCA), head and neck cancer (HNSC), lung squamous cell carcinoma (LUSC), melanoma (SKCM), and sun-exposed/unexposed skin (Fig. 2C-I). This evidence concerns the gene FSTL1 and head and neck cancer.