Human Caucasian foetal foreskin fibroblast (HFFF2) was cultured at 37 ◦ C in a 5% CO2 /95% air humidified atmosphere in a RPMI 1640 medium containing 2 mM l-glutamine supplemented with 10% (v/v) heat-inactivated FBS (fetal bovine serum), 100 IU/mL penicillin and 100 mg/mL streptomycin (Gibco).