MYCN and neuroblastoma: Only 12 of 31 nf1a-/-;nf1b+/+;MYCN;EGFP;wt-GRD;mCherry fish developed neuroblastoma tumors by the age of 12 weeks (38.7%, Figure 7A), compared to 35 of 41 nf1a-/-;nf1b+/+;MYCN;EGFP fish (85.4%, p<0.0001; Figure 7A), indicating that restoration of the NF1 GAP activity significantly reduced the penetrance of neuroblastoma in the nf1a-/-;nf1b+/+;MYCN;EGFP background.