Activation of the minimal human EPO promoter by Wt1(–KTS) in U2OS cells. Relative luciferase activities measured in lysates of human osteosarcoma U2OS cells. The cells were transiently transfected with a pGL2 reporter vector containing the minimal human EPO promoter either as wild-type (p117, top 3 boxes) or with a mutated (mutant C in Table 1) Wt1(–KTS) binding site (mut p117; bottom 3 boxes). Wt1 expression constructs encoding different splice variants—Wt1(–KTS) or Wt1(+KTS)—were cotransfected along with a cytomegalovirus promoter–driven β-galactosidase expression vector for normalization of transfection efficiencies. pCB6⁺ is the empty expression vector. Values are shown as mean ± SEM of 5 experiments, each performed in duplicate. *P < .05; ANOVA.