GBP1 and infection: To assess the involvement of the lysosomal, proteasomal and caspase pathways in PRRSV-induced reduction of GBP1, Marc-145-GBP1-flag cells were pre-treated with DMSO, proteasome inhibitor MG-132 (5 μM), autophagy inhibitor 3-MA (10 mM), and the caspase inhibitor (Z-VAD-FMK, 10 μM) for 12 h, followed by infection with a 0.1 MOI of PRRSV, and the protein expression levels of GBP1 were detected by Western blotting.