EGFR and Hippo signaling pathways both control growth and, when dysregulated, 
contribute to tumorigenesis. We find that EGFR activates the Hippo pathway 
transcription factor Yorkie and demonstrate that Yorkie is required for the 
influence of EGFR on cell proliferation in Drosophila. EGFR regulates Yorkie 
through the influence of its Ras-MAPK branch on the Ajuba LIM protein Jub. Jub 
is epistatic to EGFR and Ras for Yorkie regulation, Jub is subject to 
MAPK-dependent phosphorylation, and EGFR-Ras-MAPK signaling enhances Jub binding 
to the Yorkie kinase Warts and the adaptor protein Salvador. An EGFR-Hippo 
pathway link is conserved in mammals, as activation of EGFR or RAS activates the 
Yorkie homolog YAP, and EGFR-RAS-MAPK signaling promotes phosphorylation of the 
Ajuba family protein WTIP and also enhances WTIP binding to the Warts and 
Salvador homologs LATS and WW45. Our observations implicate the Hippo pathway in 
EGFR-mediated tumorigenesis and identify a molecular link between these 
pathways.