PTPRO and neoplasm: We chose to further investigate the RERG locus on chromosome 12, as it turned out that the OTr in this region overlaps not only one, but two genes with previously reported tumor suppressor functions: RERG (RAS Like Estrogen Regulated Growth Inhibitor), a negative regulator of the RAS/MAPK pathway and inhibitor of cell proliferation and tumor formation29,30; and PTPRO (Protein Tyrosine Phosphatase Receptor Type O), a phosphatase that counteracts the activity of tyrosine kinases, and modulates cell cycle progression and apoptosis31,32.