AATF (apoptosis antagonizing transcription factor) was initially identified as an interaction partner of DAP-like kinase (Dlk), a member of the DAP (Death Associated Protein) kinase family of pro-apoptotic serine/threonine kinases.Human AATF has an open reading frame of 560 amino acids and contains a leucine zipper structure involved in protein-protein interactions.AATF may participate in regulation of apoptotic pathways.We have found that AATF binds with Par-4 (prostate apoptosis response-4), a pro-apoptotic protein, via the leucine zipper domain, leading to a complete blockade of the pro-apoptotic signaling mediated by Par-4.Par-4 is a leucine zipper protein of about 38 kDa that plays an important role in apoptosis of many type of cells.The par-4 (PAWR) gene was initially isolated in a differential screen for genes that are up-regulated during apoptosis of prostate cancer cells.