Treatment of ESCC cells with DFMO for 72 h resulted in a dose-dependent increase in total apoptosis (Fig. 5d), G2/M arrest and a decreased S phase cell population (Fig. 5e). Western blot analysis showed that DFMO induced an increased expression of Bax, p53, p21, p27, phosphorylation of CDK1 (Tyr15), cleavage of caspase 3 and PARP and suppressed expression of PCNA, Bcl-2 and cyclin B1.