MMP9 and osteosarcoma: It has been reported that the levels of MMP-2 and MMP-9 secretion are elevated in several types of human cancers and that these elevations are associated with a poor prognosis.99 During osteosarcoma cell invasion and migration, several lncRNAs reportedly promote or inhibit cell proliferation and invasion by regulating MMP-2 and MMP-9 secretion.100 Osteosarcoma cell invasion and metastasis and the lncRNAs associated with these processes are shown in Figure 4.