PTPRO, also known as GLEPP1, is a receptor protein-tyrosine phosphatase containing an extracellular region that contains eight fibronectin FN III repeats and a single intracellular catalytic domain. GLEPP1 plays a role in axonal guidance [], promotes osteoclastic bone resorption [], mediates chemotaxis []and can act as a tumour suppressor []. Besides "full-length"GLEPP1, which is expressed in kidney and brain, a shorter variant exists that lacks the eight FN III repeats in the extracellular domain, called PTPROt, PTPphi, or PTP-oc, and is expressed in the hematopoietic lineage only, including osteoclasts [].
