For instance, the interaction of SDC4 and RSPO3 was shown to regulate WNT/planar cell polarity (PCP) signaling during Xenopus gastrulation by a process that requires clathrin-mediated endocytosis (Ohkawara et al., 2011), and SDC1 was shown to promote signaling in multiple myeloma by presenting WNTs and RSPOs (Ren et al., 2018). This evidence concerns the gene SDC1 and plasma cell myeloma.