In the past two years, the completion of the Saccharomyces cerevisiae genome project and molecular analysis of other fungal species has resulted in the identification of a growing number of yeast AP-1 transcription factors. Characterisation of these factors indicates that, like their mammalian counterparts, they activate gene expression in response to a variety of extracellular stimuli. In particular, these factors are required for the response to oxidative stress and for surviving exposure to a variety of cytotoxic agents. Much progress has also been made in understanding how members of this family of proteins are regulated. These studies promise to further our awareness of eukaryotic stress responses and are likely to have implications for the study of mammalian AP-1.