Two days after infection of untreated HepG2 cells with the E1b-fully-deleted viruses, E1a expression (under the control of the mCMV promoter) was similar to that in infections with Ad-dl309, Ad-dl309ΔVA and Ad-dl1520 viruses (under the control of the viral E1a promoter) (Figure 5A, left panel). Here, DHTKD1 is linked to infection.