This notion is further supported by theobserved down-regulation of CFTR and CREB expression in human azoospermia testes,suggesting that abnormal CFTR-CREB pathway may be a possible cause of azoospermia.The current findings not only reveal a previously undefined role of CFTR inregulation of spermatogenesis but also provide a possible mechanism underlying thepathogenesis of azoospermia in non-CF patients. This evidence concerns the gene CREB1 and cystic fibrosis.