TGFBR1 and granulosa cell tumor: Because granulosa cells may transdifferentiate into Sertoli cells in granulosa cell tumors [12], we assessed whether there were Sertoli cell-like components in the TGFBR1-CAAcre model by immunofluorescence using an antibody directed to SRY (sex determining region Y)-box 9 (SOX9), a Sertoli cell marker (Figure S4).