SOX2 and osteosarcoma: SOX2 on one hand, directly transactivates YAP expression to antagonize the Wnt/β-catenin signaling to promote adipogenesis,124 and on the other hand, blocks the Hippo pathway by directly repressing the transcription of the Hippo activators, NF2 (Merlin) and WWCI (Kibra), leading to enhanced YAP function.125 YAP depletion causes reduction of CSCs and tumorigenicity of osteosarcomas.