Second, we rescued miR223 levels in Ras;miR223KO fish, by expressing miR223 specifically in neutrophils (Tg(kita:HRASG12V‐GFP;lyz:miR223‐TagRFP);miR223KO] (Figure S2E,F, Supporting Information), and/or macrophages (Tg(kita:HRASG12V‐GFP;mpeg1:miR223‐eGFP);miR223KO) (Figure S2G,H, Supporting Information), and observed that miR223 overexpression in either neutrophils or macrophages of 1‐year‐old Ras;miR223KO fish leads to partial rescue of tumor incidence (Figure 1J). Here, MPEG1 is linked to neoplasm.