Characterization of UXT promoter. (A) Fragments of the UXT, ChET8, c-Rel, or CMV promoters were cloned upstream of the luciferase reporter and used in transient transfection experiments. 3T3 cells were transfected with either a promoter luciferase reporter construct alone or with an E2F1 expression plasmid as indicated on the x-axis. The specific promoter used in each transfection is also indicated on the x-axis. The y-axis represents the relative activity of each construct transfected alone or with E2F1 overexpression. Ratios are relative to the individual construct activity without E2F overexpression. (B) A ChIP experiment utilizing antibodies to E2F1 (lane 1), E2F2 (lane 2), E2F3 (lane 3), E2F4 (lane 4), E2F5 (lane 5), Rb (lane 6), p107 (lane 7), p130 (lane 8), or a no-antibody control (lane 9) are shown. PCR was performed with a primer set specific to the UXT promoter. A standardized aliquot of the total input chromatin is also shown (lane 10).