CDKN1B and prostate cancer: We examined p27Kip1 nuclear accumulation in the presence of each inhibitor in DU145 prostate cancer cells (Fig. 7), and via immunocytochemistry, AZ191 (3–10 μM) was a more potent inhibitor of p27Kip1 nuclear expression (Fig. 7a) indicating that the cells were not quiescent.