YAP1 and cancer: Instead, the main mechanisms that increase YAP and TAZ oncogenic activity in vivo are the modifications of the extracellular and intracellular signals occurring during tumorigenesis, for example, the formation of a hypoxic environment, the disruption of the apico-basal cell polarization in epithelial tissues, the presence of inflammation and cell/tissue damage signals, and increased mechanical stress induced by a higher production of cellular and extracellular constituents by cancer cells [37,53,54,55,56].