We constructed PK-15 cell lines with FHC knockdown or overexpression via recombinant lentivirus infection and found that apoptotic rates increased significantly due to FHC knockdown; however, when FHC-sh1 cells were infected with CSFV or transfected with pEGFP-NS4B, the apoptotic rates were maintained at a level similar to that of FHC-shN (control) cells (Fig. 6). Here, FTH1 is linked to lentivirus infection.