PTN and neuroblastoma: In neuroblastoma cells, this leads to increased tyrosine phosphorylation of p190 RhoGAP, GIT1, and DNER (Kawachi et al., 2001; Tamura et al., 2006; Fukazawa et al., 2008), and it has been proposed that the PTN inhibitory effect on PTPRZ1 acts as a major ALK indirect activating mechanism (Deuel, 2013).