Doxorubicin and Cisplatin (Platinol) were purchased from Ebewe (Austria) and Bristol-Myers Squibb (USA), respectively. The drugs were dissolved in water for injection at a concentration of 2 mg/mL. Both drugs were kept in aliquots at 4°C. Serial dilutions of these drugs were performed in culture media, immediately before each experiment, in order to obtain the required final concentrations.