Objective    To investigate the changes of P53 pathway and cell cycle in K562 cells treated with simvastatin in molecular levels and illustrate the antiproliferative and apoptosis-induced role of P53 pathway in K562 cells when exposed to simvastatin.     Methods    K562 cells were cultured and treated with simvastatin in vitro. The apoptosis rate and cell cycle of K562 cells were measured by FCM. The transcriptional level changes of most molecules in P53 pathway and cell cycle were detected by RT-PCR. The changes of P21 protein was measured by immunohistochemistry LDP method.     Results    G

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arrest in K562 cells and significant apoptosis of K562 cells were induced by simvastatin. Most genes in P53 pathway and genes related to

cell cycle after exposed to simvastatin were expressed differentially in K562 cells. The P21 protein was up-regulated with the prolongation of simvastatin treatment time.     Conclusion    P53 pathway probably plays important roles in anti-proliferation and apoptosis of K562 cells induced by simvastatin.