Cells and cell culture: Human embryonic kidney cells HEK293, U2OS osteosarcoma, HeLa cervix carcinoma, and MCF-7 breast cancer cells were obtained from the European Collection of Cell Cultures and grown in Dulbecco’s Modified Eagle Medium (Lonza) supplemented with 10% foetal bovine serum (Gibco), 50 units/mL penicillin (Lonza), and 50 µg/mL streptomycin (Lonza) for no more than 30 passages at 37 °C and 5% CO2. Cells were routinely tested for contamination.