NIKS transduced with dominant negative p53 (p53DD), but not empty vector inactivate p53.

Shown in panel (A) is a p53-specific western blot analysis of NIKS transduced with empty retrovirus vector (pLXSN: “empty vector”) or p53DD expressing recombinant retrovirus (pLXSN:p53, “p53DD”) using the pAB421 antibody. p53DD transduced NIKS, but not empty vector transduced NIKS express a low molecular weight p53DD protein. Shown in panel (B) is a p21-specific western blot of empty vector and p53DD transduced NIKS that were treated with vehicle, 0.5 nM or 5 nM actinomycin D for 24 hours. Empty vector but not p53DD transduced NIKS had an actinomycin D dose dependent response of increasing p21 levels. Beta actin was used as a loading control. Shown in panel (C) is the G1/S ratio (percentage of cells in G1/percentage of cells in S – based upon flow cytometric analysis of PI-stained cells - see methods) of empty vector and p53DD transduced NIKS treated with vehicle or 0.5 nM actinomycin D for 24 hours. The Sen-Adichie test for parallelism was used to compare the magnitude of change in the G1/S ratio between vehicle and actinomycin D treatment for each cell line. Compared to empty vector NIKS, p53DD NIKS were attenuated in actinomycin D-induced G1/S growth arrest. An asterisk indicates p values less than 0.0001.