MSN and neoplasm: We developed an in vivo genetic system in the fly that allows us to (1) generate a patch of tissue on the dorsal thorax that is homozygous mutant for a tumor suppressor, surrounded by wild-type (WT) tissue; (2) specifically label the mutant tissue with GFP:Moe (the actin-binding domain of moesin fused to GFP), thereby labeling the actin cytoskeleton of these cells; and (3) overexpress an RNAi transgene to deplete expression of a gene of interest specifically within the mutant, labeled tissue.