PPP1R3A and infection: Also, as BAC-derived viruses express eGFP from a Human cytomegalovirus (HCMV) IE1 promoter [13] independent of endogenous lytic antigens until the BAC cassette is removed [41], [42] (so in Fig. 3A not all the eGFP+ cells infected with the revertant BAC express gN) it was difficult to be sure that eGFP+ cells transfected with the gM-T1 mutant were really low for gN, or just not supporting lytic infection.