Considering the various discovered regulatory roles of K18, like apoptosis (51, 52), mitosis (27), cell cycle progression (53), and cell signaling (54), in normal cellular physiology, as well as its frequently altered expression (upregulated or downregulated) in cancer, whether K18 plays any functional roles in epithelial tumorigenesis in addition to being a diagnostic marker for the origin of tumors has been extensively investigated. This evidence concerns the gene KRT18 and cancer.