PAK1 and central nervous system cancer: An interesting observation is that the non-coding circular RNA for PTPRZ1 transcribed from the Ptprz1 gene (hsa_circ_0133159) in a microRNA (MiR)-1261-dependent manner is highly expressed in gliomas and regulates the activation of P21-activated kinase 1 (PAK1), thus upregulating glioma cell proliferation and invasion [83].