MKI-1, an inhibitor of MASTL (microtubule-associated serine/threonine kinase-like) with an IC 50 of 9.9 μM, exerts antitumor and radiosensitizer activities through PP2A activation in breast cancer. In Vitro MKI-1 (5-20 μM) inhibits the activity of MASTL in breast cancer cells. MKI-1 (100 μM, 72 h) inhibits various oncogenic properties of breast cancer cells but showed much weaker effects on the viability of normal breast cells. MKI-1 clearly reduces both serine 62-phosphorylation of c-Myc and total c-Myc, with a decrease in ENSA phosphorylation. MKI-1 (20 μM, 16 h) reduces c-Myc stability through PP2A activation in MCF7 cells. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Western Blot AnalysisCell Line: MCF7 and T47D cells. Concentration: 5-20 μM. Incubation Time: 24 h. Result: Inhibited the phosphorylation of ENSA in MCF7 and T47D cells. Significantly inhibited the phosphorylation of ENSA in mitotic cells. In Vivo MKI-1 (50 mg/kg, ip, twice a week) reduces tumor growth and enhances the radiosensitivity of BT549 xenograft model in response to 6 Gy irradiation compared with the control group, with no notable changes in body weight, suggesting the absence of gross toxicity in the treated mice . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Five-week-old female BALB/c nude mice (BT549 cells) . Dosage: 50 mg/kg. Administration: Twice per week by intraperitoneal (i.p.) injection. Result: Reduced tumor growth. Form:Solid