RNA expression of APOBEC3s in different cell lines. The cellular RNAs isolated from several human cell lines were subjected to RT-PCR with primers for human APOBEC 3 G (hA3G), hA3B, hA3F and GAPDH. The amplified PCR products were separated by agarose gels and visualized by ethidium bromide staining. (RT-), omission of reverse transcriptase from the reactions. NC, control with no added RNA.