An analysis of 108 ESCCs and nine ESCC cell lines revealed a frequent gain of the genes MDS1 (myelodysplasia syndrome 1) and PRKCI (protein kinase C, iota), which have been implicated in neoplastic transformation, and a positive correlation between the level of PRKCI expression and tumor size, lymph node metastasis and clinical stage. Here, PRKCI is linked to esophageal squamous cell carcinoma.