Background and Objective: The cell division cycle 25 (CDC25)is a familyof highly conserved dual-specificity phosphatases that activate cyclin-dependent kinase complexes. These complexes are the main cell cycle regulators. Mammalian cells ,exposure to DNA damaging radiations such as ionizing radiation and ultraviolet light, prevent cell cycle progression by activation of checkpoint pathways and lead to cell death.

      Methods: In this study, mice were exposed to different doses of ionizing radiation. Their total cellular protein was extracted from the bone marrow. After determining and matching the protein concentrations, CDC25A phosphatase levels were measured by western blotting.

        Results: The results showed that exposure to different doses of ionizing radiation in vivo significantly increased the expression of CDC25A compared to control group (P <0.05).

        Conclusion: Exposure to ionizing radiation increases the expression of CDC25A phosphatase, which increases the possibility of tumorigenesis in that area by increasing bone marrow cell proliferation.

        Keywords: Cell Cycle, CDC25A, Ionizing Radiation, Cyclin-Dependent Kinase.