Figure 2. Metastatic gastric cancer cells exhibited more malignant behavior than primary gastric cancer cells in vitro. (A) The morphology of primary or metastatic NUGC-4 cells was observed under a microscope. (B) A CCK-8 assay was used to detect the viability of NUGC-4 (control), peritoneal metastatic NUGC-4 (NUGC-4per), liver metastatic NUGC-4 (NUGC-4liver) and lymph metastatic NUGC-4 (NUGC-4lym) cells at 0, 24, 48, 72 and 96 h. (C) A flow cytometer was used to detect the apoptosis of NUGC-4, NUGC-4per, NUGC-4liver and NUGC-4lym cells that had been incubated for 48 h. (D) A flow cytometer was used to detect the cell cycle distribution of NUGC-4, NUGC-4per, NUGC-4liver and NUGC-4lym cells that had been incubated for 48 h. (E–G) The relative levels of Cyclin D1 and PCNA in primary or metastatic gastric cancer cells were detected by western blotting. *P<0.05, **P<0.01 compared to the control group.