As a positive control for induction of lytic viral gene expression in these assays, we treated monocytes with the phorbol ester PMA (phorbol myristate acetate), which induces differentiation of monocytes to a macrophage-like phenotype and is known to result in reactivation of HCMV lytic infection within 24–48h of treatment rather than the 5–7 days needed for induction of reactivation by differentiation of monocytes to monocyte-derived mature dendritic cells (mDCs) by GM-CSF/lipopolysaccharide (LPS)13,21. Here, CSF2 is linked to infection.