HIV-1 Gag does not attenuate PMA-induced CD4 downregulation. (A) COS-1 cells co-expressing CD4 and either GFP or Gag-GFP were treated as described in Fig. 5A. Data from one representative experiment (out of three) is shown. (B) Data shown represents the mean ± SD of % undegraded CD4 remaining after 6 hours of incubation with PMA in COS-1 cells under various conditions as indicated (n ≥ 2).