MKI67 and squamous cell carcinoma: For Ki-67, the mean percentages of expression were 6% in squamous epithelium, 3% in columnar cell metaplasia, 8% in Barrett's esophagus, 13% in low-grade dysplasia, 30% in high-grade dysplasia, 25% in adenocarcinoma, and 36% in squamous cell carcinoma.