MAPK8 and neoplasm: JNK signaling plays a critical role in controlling both cell proliferation and death (Karin and Gallagher, 2005; Minden et al., 1994) and is a key regulator in many forms of cell competition (Tamori and Deng, 2011), including tumor-induced cell competition in the Drosophila adult intestine (Suijkerbuijk et al., 2016).