FIG. 9.

Model for the IFN-induced effector gene expression of HuH6 cells. The binding of IFN-α and IFN-γ to their corresponding cell surface receptors (IFN-α receptor [IFNGR] and IFN-γ receptor [IFNAR], respectively) results in the phosphorylation and nuclear translocation of latent transcription factor complexes (IFN-stimulated gene factor 3 [ISGF-3] and gamma activation factor [GAF], respectively). In the case of IFN-α, a heterotrimer consisting of STAT1, STAT2, and p48 activates gene promoters containing one or more IFN-stimulated response elements ISREs. In the case of IFN-γ, a STAT1 homodimer activates gene transcription by binding to the gamma activation site (GAS). Crosses indicate potential mutations in the genome of HuH6 cells (see the text for further details).