These findings prompted to analyze the expression of CD90 at cellular level using flow cytometry: CD90 was expressed in normal and premalignant dysplastic samples at the level of a minority of cells, ranging from 0% to 1.4%; CD90 expression was significantly higher in freshly isolated ESCC clinical samples, the percentage of positive cells ranging from 2.4% to 10% [108]. This evidence concerns the gene THY1 and esophageal squamous cell carcinoma.