Characterization of an activator and a repressor sequences in the Dlk2 promoter. NIH3T3 cells were transiently transfected with luciferase constructs encompassing different regions of the Dlk2 promoter cloned into pGL3Basic vector, along with the Renilla pRL-TK plasmid. Luciferase activity was measured 24 hours after transfection, and each luciferase value (Relative Light Units) was normalized to its corresponding value of Renilla activity. The average values of at least three independent experiments are shown. (*, ** and ***, significant versus control in Student's t-test with p-values < 0.05, < 0.01 and < 0.001, respectively).