KDM4A and osteosarcoma: Various directly targeted proteins by miR-491-5p in many cancers have been recognized such as hTERT and JMJD2A in cervical cancer [13,14], BCL-XL and EGFR in ovarian cancer [15], Wnt3a and Notch3 in gastric cancer [16,63], TP53 and Bcl-XL in pancreatic cancer [17], G-protein-coupled receptor kinase-interacting protein 1 (GIT1) in OSCC [19] and FOXP4 in osteosarcoma [20].