Thyroid transcription factor 1 (TTF-1), also known as NKX2.1, is a conserved master regulatory transcription factor involved in the development of the lung, brain, and thyroid (1). In the lung TTF-1 positively regulates the expression of several lung-specific proteins including thyroglobulin, thyroperoxidase, and surfactant proteins A, B, and C (1).
