*2.4. Cell Viability Assay*

The ATP content was determined luminometrically by the CellTiter-Glo Luminescent Cell Viability assay, following the instructions of the manufacturers (Promega, Madison, WI, USA). Luminescence was measured with an automatic microtiter plate reader, Victor 3 V, Wallac 1420, Multilabel Counter (Perkin Elmer, Waltham, MA, USA).
