Fetal bovine serum (fbs)

The human promonocytic cell line U937 was cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum (Invitrogen, Life Technologies, Monza, Italy), 100 U mL^-1 penicillin, 100 μg mL^-1 streptomycin, and 2 mm glutamine (Sigma-Aldrich, Milan, Italy) at 37 °C with 5% CO₂. The cells were dispensed at 1 × 10⁶/mL and made quiescent through overnight incubation in serum-free medium. They were then placed in RPMI 1640 medium with 2% fetal bovine serum and treated with 6 μm 27-OH (Avanti Polarlipids, Alabaster, AL, USA) or in serum-free RPMI 1640 medium and treated with 5 μm HNE (Alexis, Vinci-Biochem, Vinci, Italy). In certain experiments, cells were co-treated with anti-TLR4 (0.2 μg mL^-1), anti-IL-8 (0.04 μg mL^-1), anti-IL-1β (0.04 μg mL^-1), or anti-TNF-α (0.04 μg mL^-1) antibodies (Santa Cruz Biotechnology, Santa Cruz, CA, USA). In others cases, cells were pretreated for 1 h with 1 μm parthenolide (PTN) (Sigma-Aldrich), a specific inhibitor of NF-κB nuclear translocation. Final concentrations and incubation times for all experiments are reported in the figure legends.