KRT18 and squamous cell carcinoma: Previous reports clarified that SCCs are characterized by the expression of stratified epithelial keratins (K5, K14, and K17), focally expressed keratins (K1/K10), hyperproliferative keratinocyte keratins (K6 and K16) [30], and poorly differentiated squamous cell carcinoma keratin markers such as the keratins K8, K18, and K19 [31,32,33].