Targeted co-activation of Ras- and Src-pathways in the Drosophila eye epithelia (Ras/Src-activated tumours)—by expression of an oncogenic isoform of dRas1, ras1G12V and knockout of the negative regulator of Src, C-terminal src kinase (csk−/−)—led to the development of benign tumours in animals raised on a control diet (CD) (Fig. 1a). The gene discussed is CSK; the disease is neoplasm.