PTEN and melanoma: Since 80% of human cutaneous melanomas harbor activating hot-spot mutations in either BRAF or NRAS (e.g., BRAFV600, NRASG12, or NRASQ61) [2], we examined the nf1/pten-mutant zebrafish melanomas for spontaneous mutations at equivalent sites in the zebrafish orthologues (Supplementary Fig. S4).