In papillary carcinomas, Cyclin D1 exhibited a mean 34.74% (34.74% ± 16.32%) co-expression rate with Cytokeratin 8/18 compared with a co-expression rate of 0.70% (0.70% ± 0.93%) with Cytokeratin 5/6 (p < 0.01). This evidence concerns the gene CCND1 and papillary carcinoma.