Figure 1.

p53 function can be rapidly turned on and off in HT29-tsp53 cells by temperature switching. (A) Western blot showing the expression of p53 and p21^WAF1 in HT29-neo and HT29-tsp53 cells after incubation of cells for different periods at 32°C. (B) Western blots showing stable expression of p53 and induction of p21^WAF1 within 6 h at 32°C and the rapid loss of p21^WAF1 when switching the HT29-tsp53 cells back to 38°C. (C) Two-parameter flow cytometry diagram of cells pulse labeled for 15 min with BrdU immediately before collection. BrdU incorporation (replicative DNA synthesis) is plotted on the Y axis and DNA content is plotted on the X axis. HT29-tsp53 cells were grown at 38°C (left panels), incubated at 32°C for 24 h (middle panels), or incubated at 32°C for 24 h and then returned to 38°C for 24 h (right panels).