YAP1 and cancer: Despite these multifactorial control mechanisms, mere overexpression of Yap in the whole liver in mouse models leads to hyperplasia, organomegaly, dedifferentiation, and cancer (Camargo et al., 2007; Dong et al., 2007; Schlegelmilch et al., 2011), raising a question as to whether some layer of homeostatic growth control may be lacking in such models.