Heat-shock factor 1 (HSF1) is a transcription factor that is activated upon proteotoxic stress and coordinates induction of the heat-shock response. In this issue, Dai et al. (2007) show that HSF1 is a potent modifier of tumorigenesis and is required for tumor initiation and maintenance in a variety of cancer models. These findings add HSF1 to a growing list of non-oncogenes that could be exploited as cancer drug targets.
