In contrast, massive HIV-1 infection and higher level of GFP expression were evident in TCR-proliferated CD4+ T cells at day 8 p.i. (Figure 4D, left) but the frequency of HIV-1-infected cells was substantially decreased at day 11 p.i (Figure 4D, right) because of the strong CPE of HIV-1. Here, CD4 is linked to HIV-1 infection.