We also constructed reporter vectors in which mutations were introduced at the three Crx binding sites (Fig. 3D, mut1259, mut198, mut72, mut all). Then the Crx expression vector was co-introduced with mut1259, mut198, mut72 and mut all, respectively (Fig. 3F). The transactivaton activity by Crx was clearly reduced when mut198 or mut72 was co-introduced. On the other hand, when mut1259 was co-transfected, the transactivation activity by Crx was not altered. These results suggest that the Crx binding sites 72-bp and 198-bp upstream from the transcription initiation site are crucial for the direct regulation of mr-s transcription by Crx.