STAT3 and osteosarcoma: A recent study revealed that the loss of TIMP3 expression promotes tumor invasion via elevated IL-6 production, and predicts relapse and poor survival in patients with human papillomavirus (HPV)-infected non-small-cell lung cancer (Wu et al., 2012), Our previous studies demonstrated that activation of signal transducer and activator of transcription 3 (STAT3) by IL-6 in mesenchymal stem cells promoted the proliferation, drug resistance, and metastasis of osteosarcoma (Tu et al., 2012, 2016).