CDK9 and HIV-1 infection: Immunofluorescence confirmed that a significant fraction of the CCNT1 subunit of P-TEFb was localized to the cytoplasm (Figure 7B), consistent with a previous observation that CCNT1 and CDK9 are detected in the cytoplasm in unstimulated resting memory CD4+ T cells, the target immune cells of HIV-1 infection (Mbonye et al., 2013).