WWTR1 and osteosarcoma: Moreover, high expression levels of PP1 isoform gamma and a high rate of promoter methylation and/or the downregulation of members of the RASSF tumor suppressor family (RASSF4, 5 and 10), which negatively regulate YAP/TAZ nuclear translocation, were reported in osteosarcoma cell lines and tumors [178,194,195].