Retroviral vector genomes and Nef protein immunoblot. (A) Nef⁻ genome encodes the EGFP gene 3′ of the IRES under control of the long terminal repeat (LTR) promotor. Ψ+ packaging signal, AAAA poly(A) tail of mRNA, bp, base pairs. (B) Nef⁺ genome encodes both the HIV NL4-3 nef gene and the EGFP gene. Translation of mRNA produces 2 proteins. Lengths drawn to scale. Scale bar indicates 100 bp length. (C) Immunoblot showing molecular weight marker (first lane, figures indicate weight in kD) and Nef⁺ transduced cell lysate (second lane), highlighting a protein band of +/− 27 kD.