FOXL2 has been identified as a potential driver in the pathogenesis of adult-type GCTs.8, 9, 10 Our previous studies indicated that the Hippo/YAP pathway may play an important role in the regulation of GCT cell proliferation, migration and steroidogenesis.11 Despite this progress, the molecular mechanisms underlying GCT development are largely unknown. Here, YAP1 is linked to granular cell tumor.