Inhibition of promoter/enhancer activity of PSA by human C/EBPα and C/EBPβ. The LNCaP cells were transfected either with human C/EBPα or C/EBPβ and the full-length PSA promoter coupled to the luciferase reporter. Luciferase activity was measured in the presence (dark bars) or absence (open bars) of DHT as described in Figure 4. The results expressed as relative light units are the means ± standard deviation of 3 separate experiments. The open and dark double stars represent P values as described in Figure 4A.