Dysregulation of FGF or Wnt signalling is the basis of some cancers (Clevers, 2006; Knights and Cook, 2010), and consistent with a role for Sulf enzymes in these pathways, human SULF1 and SULF2 are also mis-expressed in cancer (Rosen and Lemjabbar-Alaoui, 2010; Vivès et al., 2014). Here, SULF1 is linked to cancer.