MMP9 and neoplasm: The mechanism of oral carcinogenesis and tumor progression demonstrated by these studies includes aberrations in the heme-metabolic pathway, modulation of miRNA-145, NOD1 and BiP expression, MMP-2, MMP-9, and cathepsin modulation, abnormal TSPO binding, RIP2-mediated NF-κB activation, MZF1-mediated VEGF binding, and activation of the receptor for advanced glycation end-products (RAGE) signaling pathway.