sentences:  Activating transcription factor
  
  Activating transcription factor, ATF, is a group of bZIP transcription factors, which act as homodimers or heterodimers with a range of other bZIP factors.First, they have been described as members of the CREB/ATF family, whereas it turned out later that some of them might be more similar to AP-1-like factors such as c-Jun or c-Fos.