Ribonuclease a from

MCF-7 cells seeded in 6-well plates (3 × 10⁵ cells per well) were grown overnight, before being subjected to co-treatment with MV (MOI 0.1) and varying concentrations of CPT (10, 30, and 50 nM) at 37 °C for 1.5 h. Subsequently, the virus-drug inocula were discarded and replaced with fresh culture medium containing the respective concentrations of CPT for 5 days incubation at 37 °C. At the end of the experiment, the cells were collected by trypsinization and transferred into 15 ml tubes, where they were washed with ice-cold PBS and then fixed overnight in 70% ethanol at 4 °C. Following fixation, the cells were washed twice with PBS and incubated at 37 °C for 30 min in PBS solution containing 10 mg/ml ribonuclease A from bovine pancreas (RNase A; Sigma-Aldrich). Propidium iodide (PI; Sigma-Aldrich; 40 µg/ml) was then added to the cells before incubation at 37 °C in the dark for 15 min, and cell cycle analysis was performed using the Beckman coulter FC500 flow cytometer (Beckman Coulter Inc.; Brea, CA, USA).