In addition to general overexpression or accumulation of YAP1 staining in tumor cells (often termed “YAP1 activation”), several members of the Hippo pathway are known to be altered in human cancer at the DNA level, including amplification of YAP1 and TAZ, as well as genomic deletions or truncating mutations in NF2, LATS1 and LATS2 [15,16]. This evidence concerns the gene YAP1 and cancer.