Tsuneki1 et al. found that PDPN-positive odontogenic tumor cells were located within areas of PCNA-positive cells and that integrin β1 was localized in the cell membrane of PDPN-positive cells in the intercellular space, whereas fibronectin and MMP-9 were deposited, indicating its close association with extracellular matrix signaling [34]. This evidence concerns the gene MMP9 and odontogenic neoplasm.