More interestingly, Ki67 staining images (magnification: 200 ×) showed that the number of positive cells stained in shMEX3A group was significantly less than that in shCtrl group, which indicated that the downregulation of MEX3A resulted in a significant decrease in proliferation ability of osteosarcoma (Fig. 4e). The gene discussed is MEX3A; the disease is osteosarcoma.