Although the overall level of CK5 and CK6 mRNA levels decreased in ESCC samples, a study has shown that almost all ESCC highly expressed CK5/6 protein, only 1 of the 64 samples showed an immunohistochemical score of CK5/6 <10%.[26] Thus, the expression difference of CK7 or CK8 was more meaningful. This evidence concerns the gene KRT7 and esophageal squamous cell carcinoma.