Transcription factors and pattern formation in the developing lung

Transcription factors expressed in the cells of the developing respiratory tract affect the transcription of mRNAs of genes, and control development and pattern formation in the lungs. An increase in the activity of the retinoic acid receptor (RAR) -beta-4 causes hyperplasia in the lung epithelium. Null mutations of the N-myc protooncogene cause lethal defects in the lung. Other transcription factors such as the products of the Hox, Hlx and Hex genes, steroid and thyroid hormone receptors are also expressed in the lungs, and affect lung development and pattern formation.