2.2  Cell culture
Cells were maintained in Dulbecco's modified Eagle's medium (J744.2) or RPMI 1640 (U937) supplemented with heat-inactivated (56 °C, 30 min) foetal calf serum, 100 U/ml penicillin and 100 µg/ml streptomycin. The cultures were maintained at 37 °C in a humidified atmosphere containing 5% (v/v) CO2 in air. Treatment of J774.2 macrophages with IFN-γ (1000 U/ml) or the different pharmacological inhibitors was performed as previously described [9–14]. U937 cells were used for all transfection assays where differentiation was initiated using 1 µM phorbol-12-myristate-13-acetate (PMA) and monitored by morphological analysis [9,15].