CA9 and HIV-1 infection: HIF-1α accumulation was consistent with the temporal induction of a gene set of hypoxia responsive genes (e.g., CA9, PFKFB4, and VEGF) in our transcriptome analysis (Figure 3 and Supplementary Tables S1 and S2) and the idea that HIF-1α enhances HIV-1 infection by binding hypoxia-responsive elements (HRE) present at the 5′-LTR [10].