MYCN and neoplasm: To test the ability of the GRD domain to rescue tumor suppression in neuroblastoma, we bred the nf1a-/-;nf1b+/+;dbh:wt-GRD;dbh:mCherry transgenic line (as in Figure 1H) with the nf1a-/-;nf1b+/+;MYCN;EGFP fish.