Transcription factor that regulates gene expression during development. Required for optimal cell growth. Homodimer. Does not form heterodimers with other family members. Predominantly nuclear in growing cells and throughout development. Detected at low levels in growing cells. Levels are higher during development and decrease again at culmination. Cells develop normally and show no evident defects. Still, these cells seem to be at a selective growth disadvantage. Belongs to the transcription factor STAT family.