PTN and neuroblastoma: The GTPase-activating protein (GAP) for Rho GTPase, p190 Rho GAP, has also been shown to be a PTPRZ1 substrate based on the observations that: (a) in Ptprz1-deficient C57BL/6 mice, phosphorylation of Tyr1105 on p190 Rho GAP is not affected by fear conditioning, while in the corresponding wildtype mice, it was decreased, and (b) PTN increases phosphorylation of p190 Rho GAP at Tyr1105 in B103 neuroblastoma cells in a PTPRZ1-dependent manner [52].