The apolipoprotein A-Ⅰis an important plasma protein which plays an essential role in transportation and metabolism of lipid,and its gene expression shows evident tissue-specificity,species-specificity and developmental stage-specificity.By the cooperation of the cis-acting elements,eg. the liver-specific-enhancer at the 5' upstream region and the positive or negative transcriptional factors such as ARP-1,HNF-4,RXRα,the apo A-Ⅰ gene is regulated to express specifically.