Intestinal crypt epithelial T84 cells form luminal structures and differentiate to intestinal enterocyte-like cells in response to IMR-90 fibroblast-secreted transforming growth factor-β when grown within three-dimensional collagen gel. In search of TGF-β regulated genes involved in this differentiation process, we isolated a TGF-β downregulated cDNA, human homologue of rat apoptosis antagonising transcription factor that codes for a 560-amino-acid protein. Human AATF-mRNA was expressed at high levels in human brain, heart, thymus, kidney, and placenta while in skeletal muscle and colon the expression was lower. The gene was mapped to chromosome 17q11.2-q12.