In this research project, we have so far obtained the following findings. First, we have established the in vitro model system of cell competition, in which co-culture of mouse embryonic fibroblast cells, NIH3T3, with different activities of the Hippo pathway transcription factor Tead family causes cell competition-like communications. We also found that cell competition observed with this system resembles those of Drosphila imaginal discs because both cell competitions involves cooperation of Myc and Tead activities (J. Cell Sci., 2015). Second, based on these findings, we also found that similar Tead activity-triggered cell competition also took place in the mouse epithelial cell line, MTD-1A (unpublished results). Finally, we also found that similar Tead activity-triggered cell competition also took place in the endoderm of early mouse embryos (unpublished results). These findings indicate that the Tead activity-triggered cell competition is a general mechanism of intercellular communications used in both epithelial and mesenchymal tissues.