Fig. (1) T-cell signaling modulation by HIV-1 proteins. HIV-1 viral proteins modulate several transcription factors and surface receptors from infected CD4+ T cells that facilitate HIV-1 infection and pathogenesis. HIV-1 viral proteins (gp120, Nef, Tat and Vpr) induce downstream signaling events to activate nuclear factor of activated T cells (NFAT), nuclear factor kappa B (NF-κB), activator protein 1 (AP- 1) and specificity protein 1 (Sp1), and to induce the efficient transcription of HIV-1 (via its long terminal repeat (LTR)), cytokines and activation markers.