The relative concentrations of interferon-gamma (IFN-c) and ornithine decarboxylase antizyme 1 (OAZ1) mRNA in all RNA samples was determined by real-time PCR. Two hundred ng of total RNA was reverse transcribed in a standard RT reaction using Superscript II reverse transcriptase (Invitrogen) and pd(N) 6 primers. IFN-c cDNA in these RT reactions was quantified using labeled Light-Cycler probes (Roche Diagnostics) as described [15] and expressed as pg/ll control plasmid. A 20-mer forward primer (5 0 -GACCCGACGCTTGCTTCATG-3 0 ) and a 19mer reverse primer (5 0 -GAGTGAGCGTTTATTTGCAC-3 0 ), generating a cDNA fragment homolog to nucleotide 702-895 of the human OAZ1 mRNA reference sequence (gi:34486089), were used to quantify OAZ1 cDNA using Cybergreen as label in a standard LightCycler reaction. The relative concentration of OAZ1 mRNA was calculated by extrapolation on a standard curve prepared from dilutions of an RT reaction prepared from a reference RNA sample [34] . The quantity of 18S rRNA in each RNA sample was determined using the above described RT reactions by real-time PCR [15] and used to normalize the IFN-c and OAZ1 concentrations. The quantity of 18S rRNA showed no essential differences among all individual RNA samples (average concentration ± SD; 4.95 ± 0.82 lg/ll of control plasmid).