Schematic representation of the HPH/SU-DHL-4 co-culture model utilized in the current studies (A). Concentration- (B) and time-dependent (C) anticancer activity of CPA and CHOP chemotherapy in the presence and absence of CITCO. Cells in co-culture were treated with CPA or CHOP (5, 50, 100, 250, 500 μM) in the presence of CITCO (1 μM) or vehicle control (0.1% DMSO) as detailed in Materials and Methods. Viability of SU-DHL-4 cells under these treatments was determined at 0, 24, 48, and 72 h. Data represent the mean ± S.D. of three independent measurements normalized as percent viability of vehicle control. Statistical significance between the treatment groups 0.1% DMSO/CHOP and CITCO/CHOP were analyzed (*, p < 0.05).