Celastrol repressed viability of gastric cancer cells and NF-κB signaling pathway. Exposure to various concentrations of celastrol resulted in dose- and time-dependent growth inhibition of BGC-823 cells (A), SGC-7901 cells (B), MGC-803 cells (C) and GES-1 cells (D). Celastrol inhibited phosphorylation of IκB and nuclear p65 content in dose-dependent manner (E). Celastrol decreased NF-κB transcriptional activity in BGC-823 cells, SGC-7901 cells and MGC-803 cells in a dose-dependent manner (F). *P < 0.05, indicate significant differences from the respective control groups.