It was also reported that MMP2 in renal carcinoma cells, MMP9 and MMP14 in osteosarcoma cells could increase soluble MICA [23, 24, 40, 41] and MMP9 specific inhibitor could increase MICA/B and ULBP2 in some kinds of gastric cancer cells [19]. Here, MMP9 is linked to osteosarcoma.