Cell cycle distribution of 3T3 and 3T3BXB-ER cells after prolonged activation of BXB-ER and BXB-ER induced accumulation of p21.

<p>(A) Cell cycle analysis of 3T3 and 3T3BXB-ER cells. Exponentially growing cells were left untreated (first panel) or activated with estrogen for 8 or 24 hours. Cells are gated into different cell cycle stages (as outlined in the figure) dependent on their total DNA content (Propidium Iodide intensity, F1 abscissa, ranging from 2N for cells in G1-phase to 4N for cells in G2-phase) and the amount of BrdU incorporated into the genomic DNA in the last 3 h before processing (ordinate, BRDU, low BRDU intensity for cells in G1- and G2-phase, high BRDU intensity for S-phase cells). (B) shows the numerical analysis of the FACS results - percentages are shown as percent of all gated cells. (C) Western blot for p21. Exponentially growing 3T3 and 3T3BXB-ER cells were left untreated or incubated for the indicated times with estrogen and blots were processed in parallel. 20 µg of protein from the various whole cell lysates were loaded into each lane. The parts of the blots where p21 migrates are shown.