Fig 1: Addition of curcumin enhances apoptosis induced by DOX in K562/DOX cells. (A) Effects of curcumin (2 µM), DOX (4 µM) and si-S100A8 used alone or in combination on the intracellular free calcium ion concentration in K562/DOX cells. Effects of curcumin (2 µM), DOX (4 µM) and si-S100A8 used alone or in combination on the protein expression of (B) Bcl-xL, Bax and (C) CHOP in K562/DOX cells. (D) Effects of curcumin (2 µM), DOX (4 µM) and si-S100A8 used alone or in combination on caspase-3 activity. (E) K562/DOX cells were stained with DAPI after pre-treatment and observed under an inverted fluorescence microscope (magnification, ×40) and the relative fluorescence intensity analysis of DAPI was determined. DNA fragmentation is indicated by red arrows. ***P<0.001. DOX, doxorubicin; K562/DOX, DOX-resistant K562 cell line; S100A8, S100 calcium-binding protein A8; Bcl-xL, B-cell lymphoma extra-large; Bax, Bcl-2-associated X protein; CHOP, CCAAT/enhancer-binding protein homologous protein; si-S100A8, small interfering RNA targeting S100A8.