Mechanistic model for the cytoprotective effect of HIV-1 infection and Tat expression. A summary of the findings induced by HIV-1 infection and intracellular Tat expression, including the mechanistic actions leading to activation of the PI3K/Akt pathway and subsequent long-term survival of macrophages, is shown. Observed alterations in the signaling pathway induced by HIV-1 infection are shown in block arrows. The dotted arrow indicates an alternative possible cytoprotective effect caused by p53 downregulation. Akt with asterisk denotes the activated/phosphorylated form of the protein.