PCNA and gastric cancer: Western blot analysis showed that exposure to 0/5/10/30 μmol/l sanguinarine increased DUSP4 and Bax expression, but decreased the expressions of p‐ERK, and its downstream signalling molecules in GC cells, such as PCNA, MMP‐2 and Bcl‐2, involved in cell proliferation, invasion and anti‐apoptosis, respectively (Fig. 5B).