| With selected mutations in ER alpha and signal transducer and activator of transcription 3 ( Stat 3 ) , we demonstrated that the blockade of TGF alpha mitotic potential was not dependent on ER alpha DNA binding activity but required a transcriptionally active Stat 3 . ^^^ Based on the data presented , we hypothesized that in the presence of prothymosin alpha , ER alpha activates its direct target genes and increases cell proliferation , whereas in the presence of high levels of TGF alpha , ER alpha preferentially interacts with Stat 3 and causes cell differentiation . ^^^ |