Using cDNA microarray analysis, we found that the mRNA of YJL217W and several other genes related to cell wall organization and biogenesis were up-regulated by galactose in Saccharomyces cerevisiae early during the induction process. YJL217W is also known as REE1 (Regulation of Enolase I). Both the Gal4 regulatory region and the Mac1 binding domain were found on the upstream region of REE1, and the expression of REE1 was up-regulated by galactose but not by glucose. The up-regulation of REE1 by galactose was not observed in the Deltagal4 strain. From the two-hybrid analysis, we found that Ree1 physically interacted with Gal83. Furthermore, from 2-D gel electrophoresis we found that the deletion of REE1 resulted in the up-regulation of Eno1. From Western blotting, we learned that the expression of Eno1 in the Deltaree1 strain was different from that in wild-type strains and that Eno1 expression was not changed by glucose stimulation. Taken together, these results suggest that Ree1p functions in the galactose metabolic pathway via the Gal83 protein and that it may control the level of Eno1p, which is also affected by the Snf1 complex, in S. cerevisiae.