Inhibits glioma cells invasion and down-regulates adhesion- and motility-associated genes such as NFKB2 and ICAM1. Exhibits opposing effects to IGFBP2 on cell invasion. Interacts with IGFBP2. Ubiquitous. Isoform 1 is expressed in brain but underexpressed in glioma tissues, at protein level. Isoform 2 is not detected in normal organs, but is expressed in gliomas with increasing levels with glioma progression. On the contrary, at protein level, isoform 2 is not detected in gliomas, suggesting that this isoform is unstable in glioma cells. Up-regulated by IGFBP2. Isoform 2 is degraded by the ubiquitin-proteasome pathway.