(A) Chemical structure of APIO-EE-9. (B) Cytotoxicity of APIO-EE-9 was assessed by MTS assay in the normal Het-1A esophageal cancer cell line. (C) KYSE450, KYSE30 and KYSE510 esophageal cancer cell lines were treated or not treated with various concentrations of APIO-EE-9 and anchorage-independent growth was measured. Data are shown as mean values ± S.D. from triplicate experiments. The asterisks (**) indicate a significant (p < 0.01) decrease in colony formation compared to the control group. (D) KYSE450, KYSE30 and KYSE510 esophageal cancer cells were treated with different concentrations of APIO-EE-9 and viability of estimated. Data are shown as means ± S.D. from triplicate experiments. The asterisks (*, **) indicate a significant (p < 0.05, p < 0.01, respectively) decrease in viability compared to the control group.