CCN1, CCN2, CCN3 and CCN4 are all poorly expressed in healthy adult bony tissues, but they are up regulated in primary samples as well as osteosarcoma cell lines (Chen et al. 2013a; Fromigue et al. 2011; Habel et al. 2019; Huang et al. 2016; Liu et al. 2017b; Perbal et al. 2008; Tsai et al. 2014a, 2014b, 2014c; Wu et al. 2013; Zhang et al. 2013). The gene discussed is CCN4; the disease is osteosarcoma.