FGF23 and cancer: ppGalNAc-T3 serves as an important test case as it is implicated in at least two medically important pathways: cancer metastasis and stabilization of FGF23 (Chefetz and Sprecher, 2009; Schjoldager et al., 2011; Kato et al., 2006; Peng et al., 2012; Kohsaki et al., 2000; Kitada et al., 2013; Gao et al., 2013; Brockhausen, 2006; Brooks et al., 2007).