Figure 1. Cellular and molecular mechanisms underlying CIN-induced tumorigenesis in Drosophila epithelia. (A) CIN-induced tumorigenesis reproduces key aspects of human cancer, including cell delamination, hyperplasia, basement membrane (BM) degradation and invasiveness. Aneuploid cells (blue) lose their apicobasal polarity and delaminate from the epithelium (red). Delaminating cells activate the stress-responsive JNK signaling pathwa,y which, in turn, leads to the expression of at least two downstream targets genes, wingless and the matrix-metalloproteinase-1 (MMP1). Wingless contributes to the hyperplastic overgrowth of the monolayer epithelium (B), while MMP1 has an active role in degrading the BM, a critical step in tissue invasiveness (C).