passages.id: split_7_validation_194_passage
passages.type: progene_text
passages.text: The induction of Sertoli cell differentiation appears to involve the serum response element ( SRE ) of the c-fos promoter to activate c-fos and intermediate bHLH factor(s) that regulate down - stream Sertoli cell - differentiated genes ( e.g. transferrin expression ) .