Curcumin reduced proliferation and viability of CRC cell lines with high or moderate MACC1 expression. CRC cells were treated with various concentrations of curcumin. Every 2 h, the confluency of the cells was assessed by a cell imaging system. Curcumin significantly reduced the proliferation of the cells with high or moderate MACC1 expression (SW620/KO-Control, HCT116/KO-Control) (A). Cell viability was determined using the MTT assay. Viability of the CRC cells was reduced upon curcumin treatment in a dose-dependent manner (B). Data represent mean ± SEM (n ≥ 3), * = p < 0.05, ** = p < 0.01, *** = p < 0.001, **** = p < 0.0001.