In contrast to the abundance of TRAIL transcripts, mRNA levels of FasL and TNF-a were barely detectable by realtime RT-PCR in swine macrophages (data not shown). However, both FasL and TNF-a were induced profoundly in response to pH1N1 infection ( Fig. 2B and 7A-C) , while the change of TRAIL was mild. By using inhibitors, we concluded that the induction of FasL and TNF-a are mainly controlled by the ERK1/2 and JNK1/2 pathways in pig macrophages.