PTPRZ1 and glioblastoma: However, there are also studies showing a negative effect of PTN in GBM cell growth and migration [8,132], and we have shown that the stimulatory or inhibitory effect in GBM cell migration depends on the expression of ανβ3 integrin [30], suggesting that the tumor microenvironment should be considered in each case, and identification of proper biomarkers should precede the use of PTPRZ1 TP inhibitors.