MG132 is known to have off-target effects, e.g., it inhibits calpain and clasto-lactacystin β-lactone which inhibits cathepsin A. Although Schwartz et al.56 showed that treatment of target cells with the proteasome inhibitors MG132 and lactacystin increased the early steps of HIV infection, Schubert et al.19 demonstrated that virus assembly, maturation and budding require an active proteasome system. Here, CTSA is linked to HIV infectious disease.