PTPRZ1 and glioblastoma: An additional receptor of IL-34, receptor-type protein-tyrosine phosphatase ζ (PTPRZ1, RPTP-ζ), was recently identified by Nandi and colleagues who showed signalling through PTPRZ1 by IL-34, but not CSF-1, in mouse brain and in the human glioblastoma cell line U251 [11].