However, the mean Cyclin D1 protein (0.914 ± 0.537 vs. 0.684 ± 0.381, P < 0.05) and mRNA (1.980 ± 0.592 vs. 0.442 ± 0.317, P < 0.05) expression levels in the ESCC tissues were higher than the corresponding levels in the adjacent tissues. This evidence concerns the gene CCND1 and esophageal squamous cell carcinoma.