MMP9 and gastric cancer: In our study, AP-1 decoy oligodeoxynucleotides, AP-1 inhibitor curcumin, c-Jun and c-Fos siRNA interfered with PMA-induced MMP-9 expression (Fig 2A–2D), which provided direct evidence that AP-1 is critically required to increase MMP-9 transcription in gastric cancer cells.