Promoter activity of the deletion regions with/without the Ap-1 site. The deletion constructs with/without the Ap-1 site were amplified and then inserted into the pGL3-basic vector. The promoter activities of the constructs were analyzed by transfection into the CHO-K1 cells. The -306-Luc fragment has an Ap-1 site (5′-TGTCTCAT-3′) from -281 to -274. The -273-Luc fragment does not have an Ap-1 site.