XBP1 and osteosarcoma: The genes of TFs (XBP1(Yang et al., 2015; Yu et al., 2022), ATF4 (Luo et al., 2017, 2019; Xian et al., 2017), and SOX9(Y. Chen S. et al., 2020; He et al., 2017; Wang et al., 2018)) were significantly activated in osteoblastic cells (Figures 11A–D), and were demonstrated to be expressed in osteosarcoma.