Tpo upregulates the promoter conformation of p53 in M07e cells. After an 18-hour factor starvation period, 1 × 10⁶ cells were treated with either Tpo (50 ng/mL), GM-CSF (GM; 100 U/mL), or control serum-free media for 24 or 48 hours. (A) The cells were prepared for flow cytometric analysis for the detection of immunologic variants of p53. The individual cultures were split into four equal groups and treated with either suppressor conformation-specific IgG2_a Pab 1620, an IgGa₂ isotype control, promoter conformation-specific IgG1 Pab 240, or the IgG1 isotype control. These cultures were then all stained with anti-IgG FITC conjugated secondary antibody. (B) p53 was immunoprecipitated from cell lysates at the indicated time points with either Pab 1620 or Pab 240, transferred to membrane by SDS-PAGE, and probed for p53 with sheep α-p53. This figure represents flow data from four experiments and Western blot data from two experiments which yielded similar results.