To measure the percentage (%) of cells outside the G0 phase, an intracellular staining with Ki-67 was also performed, and we confirmed higher SAMHD1 expression in cells that were in cell cycle arrest as a consequence of saturation density or serum starvation (Ki-67+ cells: 0%) compared to proliferating cells (Ki-67+ cells: 20%); however, the levels of SAMHD1 were much higher upon HCMV infection (Ki-67+ cells: 62%) (Fig 2g). This evidence concerns the gene SAMHD1 and cytomegalovirus infection.