R-spondin (RSPO)-3, a member of the RSPO family of matricellular signaling proteins involved in vascular homeostasis (Aoki et al., 2007; Knight & Hankenson, 2014; Scholz et al., 2016) promotes oncogenesis in solid tumors (Chartier et al., 2016; Marcucci et al., 2016; Picco et al., 2017) and hematologic malignancies (van Andel et al., 2017; Wang et al., 2013). This evidence concerns the gene RSPO1 and hematologic disorder.