ZNF506 and infection: Finally, we calculated the copy numbers of the pMX-RFP pseudoviruses in infected ZNF506–GFP and ZNF417–GFP 293T cells at different stages, including 12 h after infection to test early reverse transcription (early RT), 24 h after infection to test late reverse transcription (late RT) and 48 h after infection to test viral integration into the genome (51).