CTTN and HIV-1 infection: This is also the first study, to our knowledge, to show that 1) HIV-1 infection in humans is associated with increased transcription of RAC1 and CTTN, 2) Rac1 phosphorylation at S71 is increased in HIV+ brain tissues, and 3) cells expressing phosphorylated Rac1 (S71) in the human brain were mostly associated with brain macrophages and blood vessels.