For example, CK18 positivity has been described in 30% to 100% of oral squamous cell carcinomas (Nanda et al. 2012; Safadi et al. 2019), 0% to 100% of non-small cell lung cancers (Chen et al. 2011; Nhung et al. 1999), and 0% to 43% of esophageal squamous cell carcinomas (Makino et al. 2009; Ishida et al. 2017). Here, KRT18 is linked to esophageal squamous cell carcinoma.