In contrast to HBV infection, HDV infection of susceptible cells, including differentiated HepaRG cells and exogenous NTCP-expressing hepatoma cells (HepG2 or Huh7)14, 15, leads to high levels of viral replication (>300,000 copies per cell), which is easily detected by northern blot hybridization. The gene discussed is SLC10A1; the disease is hepatocellular carcinoma.