MMP9 and pancreatic neoplasm: In particular, Guan et al. reported that PAIP1 knockdown in pancreatic cancer cells markedly decreased in the expression of MMP2, which affects the invasion and migratory process and MMP2 in OSCC has also been described as a potential biomarker for metastasis15,29–33, whereas we found no change in the MMP2 levels, rather MMP-9 activity downregulation in the PAIP1 knockdown of OSCC cells (Figs. 4d and S6)15.