Importance of USF in Breast Cancer.

USF is a family of transcription factors whose function in growth control can antagonize the transforming activity of the Myc oncoproteins. We are investigating the role of USF in breast cancer. Normal USF DNA-binding activities were observed in a variety of breast cancer cell lines. However, cotransfection experiments revealed a complete lack of USF transcriptional activity in at least three different breast cancer cell lines. This result suggests that, like the overexpression of Myc, the functional inactivation of USF may play an important role in breast cancer by favoring rapid proliferation rates.