Because human NF1-mutant melanomas often harbor gain-of-function alterations in the PI3K signaling pathway, including mutational inactivation of PTEN or overexpression of AKT3 [2, 5], we introduced pten loss-of-function mutations into nf1a+/−;nf1b−/−;p53M214K/M214K zebrafish by crossing with a previously established ptena+/−;ptenb−/− line [16, 17]. The gene discussed is PTEN; the disease is melanoma.