Overexpression of Sp1 increases transcription from the proximal promoter in HeLa cells, whereas overexpression of Sp3 does not reduce transcription in PC3 cells.

(A) HeLa and (B) PC3 cells were cotransfected with the reporter construct in which the uPA proximal promoter drives luciferase transcription and with expression vectors for Sp1 and Sp3, respectively. (A) Overexpression of Sp1 increases transcription of the luciferase construct in HeLa cells, whereas (B) overexpression of Sp3 does not affect transcription of this construct in PC3 cells.