Figure 4. Sox2 activates endogenous VRK1 gene expression.

(a) Effect of Sox2 overexpression in MDA-MB-231 cells infected with the retroviral plasmid pBabe-Sox2. Cells were studied by confocal immunofluorescence and the quantification of the fluorescence is shown in the graph (right). (b) Effect of Sox2 overexpression on endogenous VRK1 protein in cell lysates of MDA-MB-231 cells determined by immunoblot. (c) Levels of endogenous VRK1 RNA from control or infected MDA-MB-231 cells with pBabe-Sox2. Sox2 and VRK1 RNA levels were determined by qRT-PCR. (d) Effect of overexpression of Sox2 on the proximal VRK1 promoter (−1028 + 52) in a luciferase reporter construct. At the bottom is shown the expression of transfected Sox2. Reporter gene experiments were performed three times, and each individual luciferase assay was determined in triplicate.