A typical experiment reporting the time course of R-399 replication in human HER2-positive SK-OV-3 cells and in the murine CT26 tumor cells transgenically expressing human HER2 (CT26-HER2) is shown in Figure 2A. The growth of R-399 was about half a log lower than that of R-337 in SK-OV-3 cells; in CT26-HER2 cells, it was delayed, which was consistent with the mild defects in infection dynamics seen in Figure 1 and reached substantially similar titers at 48–72 h after infection. Here, ERBB2 is linked to infection.