SPP1 and cancer: Moreover, Ran has been shown to be a key player to mediate signaling pathways originating from well-documented cancer metastasis promoters such as the glycophosphoprotein osteopontin (OPN) [reviewed in Zhao et al. (2018)], the RNA-binding protein LIN28B (Balzeau et al., 2017; Lu et al., 2018; Yong et al., 2018; Zhang et al., 2018, 2019), and the oncogene c-Myc (Wolfer et al., 2010; Wolfer and Ramaswamy, 2011; Dang, 2012).