Fig. 4. p53-dependent transcriptional activity in TNF-treated MEFs. MEFs were transfected with the firefly luciferase gene under the control of the p53 responsive element derived from the mdm2 gene in combination with empty vector alone (Control), or MKK3, or Cdc42-N17, or N-Wasp, or KD-MKK3 or p53 wt as positive control. As indicated, cells were treated with either TNF, or SB 203580, or both. The luciferase activity was assayed 24 hours later. The results are expressed as means±s.d. of four independent experiments.