Through the expression of Cas9 under the control of the mitfa promoter in F0 mosaic zebrafish, Ablain et al. [83] showed that the melanocyte-specific targeting of spred1 in addition to ptena/b and tp53 results in late-onset melanomas, which is not observed through ptena/b and tp53 targeting alone. The gene discussed is SPRED1; the disease is melanoma.