Only cells that emitted both green (EGFP, indicating transfection) and red (RFP, indicating infection) fluorescence were recovered and equal numbers of infected cells that expressed EGFP, EGFP-PML IV or EGFP-PML IV-Δ8AB were added to permissive cell monolayers and observed for plaque formation (Figure 10A–C). This evidence concerns the gene PML and infection.