USF-1 directly regulates ILEI transcription.
A, luciferase assay of the ILEI promoter reporter construct (−300/−80) in 501-Mel melanoma cell lines. 0, 0.05, 0.1, 0.2, and 0.4 μg of experimental vector and a corresponding 0.4, 0.2, 0.15, 0.1, or 0 μg of empty vector were transfected for 24 h. The increased darkness of the bars indicates increased experimental vector. Luminescence is normalized to vector control for each transcription factor. n = 3, mean ± S.D., * indicates p < 0.01 by Student's t test as compared with vector transfection. B, ILEI promoter sequence from −189 to −125 highlighting E-box and initiator (Inr) motifs. C, various ILEI promoter luciferase reporter constructs either WT or mutant for the E-box or the Inr. D, luciferase assay of ILEI promoter reporter constructs in 501-Mel melanoma cell lines. Black bars indicate vector overexpression and white bars indicate USF-1 overexpression. n = 3, mean ± S.D., p value indicated by Student's t test as compared with vector.