<prompt> What is the half-life of p53 protein in normal cells?20 minutes60 minutes12 hours1 day  <response>: In non stressed, healthy cells, p53 has a sho half-life 20 minutes, because of its association with MDM2, a protein that targets it for destruction. When the cell is stressed, for example by an assault on its DNA, p53 undergoes post-transcriptional modifications that release it from MDM2 and increase its half-life. Unshackled from MDM2, p53 also becomes activated as a transcription factor. Ref: Robbins 8th edition Chapter 7. 