Tan IIA increased the effects of CDDP/5-FU-based chemotherapy by inducing apoptosis. (A and C) CAL27 and SCC4 cells were treated with 2 μM Tan IIA, 2 μM CDDP or combination. The cell lysate was subjected to IB analysis (A). MTS analysis of cell viability (C). (B and D) CAL27 and SCC4 cells were treated with 2 μM Tan IIA, 20 μM 5-FU or combination. The cell lysate was subjected to IB analysis (B). MTS analysis of cell viability (D). (E) CAL27 cells were treated with 2 μM Tan IIA, 2 μM CDDP or combination, and then were subjected to Immunofluorescence (IF) analysis with cleaved-Caspase 3 antibody. (F and G) CAL27 and SCC4 cells were treated with 2 μM Tan IIA, 2 μM CDDP or combination. The cell lysate was subjected to IB analysis. (H) The tumor volume of CAL27-derived xenograft tumors treated with vehicle, Tan IIA, CDDP, or combination. (I and J) IHC staining of Ki67 and PUMA in CAL27-derived xenograft tumors treated with vehicle, Tan IIA, CDDP, or combination. Scale bar, 25 μM, ***, p < 0.001.