OLIG2 and brain neoplasm: Based on this, a zebrafish model of CNS NB-FOXR2 was generated using an I-SceI-mediated transgenesis system by activating NRAS in Olig2 and Sox10 expressing OPCs in homozygous p53M214K; mitfaw2 embryos (lacking p53 activity and deficient in pigment (melanophore)), which displayed brain tumour onset by 6 weeks post fertilisation (wpf).