Fig. 4

Curcumin inhibits JAK2 phosphorylation in ESCC cells. a Molecular modeling of curcumin/JAK2 complex. a 3-D presentation of the molecular docking complex pose (curcumin colored in green), b 2-D presentation and c 3-D presentation of the interactions between curcumin and the key residues of JAK2 (curcumin colored in green, the residues colored in orange, the H-bond colored in red). b Following starved overnight in serum-free medium, EC9706 and TE13 cells were incubated with 0, 8 or 16 μM curcumin for 4 h, then stimulated with IL-6 (50 ng/ml) for 20 min. The cells were lysed and analyzed by immunoblotting against p-JAK2, JAK2 and GAPDH. c EC9706 and TE13 cells were treated with different concentrations of curcumin for 24 h. Then, cells were prepared for immunoblotting against p-JAK2, JAK2 and GAPDH. d JAK2 activity analyses in an in vitro cell-free system. Increasing concentrations of curcumin were incubated with JAK2, and the activity of JAK2 kinase was determined with HotSpot technology. ^*p < 0.01, ^**p < 0.001