Introduction: The p53 gene is well-known to impede carcinogenesis by inducing apoptosis. p63 is a recently discovered relative of the p53 gene family. The biological function of p63 is still under investigation. DeltaNp63alpha is an isoform of DeltaNp63 that lacks the transactivation domain. Its function may be to act as an “anti-p53”. We evaluated the effect of Cisplatinum on apoptosis and the expression of DeltaNp63alpha in three rat-cell lines: JA, JB and AMY. These cell lines were derived from our reflux model of esophageal carcinoma. Methods: A mouse monoclonal antibody against all p63 isotypes (4A4) (Santa Cruz Biotechnology, Santa Cruz, CA) and a rabbit polyclonal antibody against the N-terminus of DeltaNp63 isotypes (p40Ab-1) (Oncogene Science Inc., Cambridge, MA) were used in this study. Cell proliferation was evaluated using the MTT cell proliferation assay kit (ATCC reg.). Apoptotic cells were identified with anti-active caspase-3 pAb (Promega) staining. Apoptosis was initiated by Cisplatinum (Sigma) treatment. Results: First, we found a direct correlation between p63 expression and the rate of cell growth with the JA and JB cell lines growing faster and with more p63 expression than the AMY cell line (Fig. 1). Secondly, we found that Cisplatinum induced apoptosis, while reducing levels of DeltaNp63alpha in the JB cell line (Fig. 2-3). Conclusion: We conclude that Cisplatinum may induce apoptosis by diminishing DeltaNp63alpha levels and thereby allowing p53 to be more active in inducing apoptosis in this cellular model of esophageal cancer.