A schematic figure shows the relationship between FN and HBV.

HBV increases FN expression through activation of Sp1. In turn, induced FN facilitates HBV replication and expression via two distinct mechanisms: 1) FN binds to the TAK-TAB complex, inhibits phosphorylation of TAK1 and reduces the nuclear translocation of NF-κB p65 to decrease endogenous IFN-α production; 2) FN activates HBV EII activity by mediating the binding of liver-specific factor HNF-4α.