At late stages of infection (48 hpi), when US18 and US20 are de novo expressed (see Fig. EV2D), BMP9 stimulation led to higher SMAD1/5/9 phosphorylation levels in HFF-1 infected with HCMV lacking US18/20 compared to HCMV WT, indicating that also de novo expressed US18/US20 downregulate BMP signaling at this time point of infection (Fig. 8C). The gene discussed is SMAD1; the disease is infection.