MYCN and neuroblastoma: As a control, we also stably expressed the inactive GRD R1276P mutant (designated 'mut-GRD') into nf1a-/-;nf1b+/+;MYCN;EGFP fish, which led to a frequency of neuroblastoma at 12 weeks of age that was identical to that in fish not transgenic for either GRD construct (90.0%, Figure 7A).