WIF1 and osteosarcoma: WIF1 silencing by hypermethylation and consequent Wnt signaling activation has been demonstrated in numerous cancers such as nasopharyngeal cancer [17], lung cancer [18], mesothelioma [19], breast cancer [20], urinary bladder cancer [21], renal cancer [22], osteosarcoma [23,24] and gastric cancer [25].