Interleukin-34 (IL34) signals via the Colony-stimulating factor-1 receptor (CSF1R). It can also bind Receptor-type protein-tyrosine phosphatase zeta (PTPRZ1), a cell surface chondroitin sulfate (CS) proteoglycan. PTPRZ1 is primarily expressed on neural progenitor and glial cells. IL34 selectively bound PTPRZ1 in CSF1R-deficient U251 human glioblastoma cell lysates, inhibiting proliferation, clonogenicity and motility, and promoting an increase in tyrosine phosphorylation of focal adhesion kinase 1 (PTK2) and paxillin (PXN) (Nandii et al. 2013).