p73, a p53-related gene, is essential for a development of animals, while p53 is important for tumor formation. And little is known about the target genes specifically regulated by p73. Identifying the specific targets of p73 is important to understand the physiological roles of p73. To identify the genes specifically regulated by p73, we conducted serial analysis of gene expression to quantitatively evaluate messenger RNA populations. We found that the gene for phosphatidic acid phosphatase 2a (PAP2a), an enzyme that hydrolyzes lipids to generate diacylglycerol, was specifically upregulated by ectopic production of p73 beta. The promoter region of this gene contains an element that is functionally responsive to p73 beta. And the quantity of PAP2a protein was upregulated by ectopic production of p73 beta. These results suggest that the expression of PAP2a is directly regulated by p73. (c) 2006 Elsevier Inc. All rights reserved.