Figure 3. Metastatic gastric cancer cells were more invasive than primary gastric cancer cells in vitro. (A, B) NUGC-4, NUGC-4per, NUGC-4liver and NUGC-4lym cells were incubated for 48 h, and their migration was investigated by a Transwell assay. (C, D) A Transwell assay was used to investigate the invasion of NUGC-4, NUGC-4per, NUGC-4liver and NUGC-4lym cells. (E–G) The relative levels of p-Smad2 and p-Smad3 in metastatic or primary gastric cancer cells were detected by western blotting. (H) The levels of TGF-β in supernatants of metastatic or primary gastric cancer cells were detected by ELISA. *P<0.05, **P<0.01 compared to the control group.