Figure 4. Failure of Vim409 to drive eGFP expression in cells that lack endogenous vimentin expression

A: Müller cells transfected with 2 μg of the Vim409 plasmid construct for 24 h. The construct included the upstream hybrid CMV/LTR and the TB element. B: Müller cells transfected with 2 μg of the Vim409 plasmid after removing the CMV/LTR. Expression of eGFP was indistinguishable between A and B. C: Cultured T24 cells transfected with 2 μg of the Vim409 plasmid construct for 24 h. D: Cultured T24 cells transfected with 2 μg of the Vim409 plasmid after removing the CMV/LTR. Note the near complete loss of expression when the CMV/LTR is removed, validating the specificity of the Vim409 promoter for directing expression in vimentin-positive cells, and indicating that expression in C is due to the CMV/LTR promoter driving expression through the TB in a subset of cells. Scale bar in A represents 100 μm.