Important NF-κB transcription factor signaling in monocyte-macrophages. (a) Activation of HIV transcription: Translocation of NF-κB from the cytoplasm to the nucleus is controlled by association of IκB with the NF-κB hetero-/homo-dimer. Once IκB is phosphorylated, it relesases NF-κB which then translocates to the nucleus where it can bind the LTR and induce HIV transcription. (b) Inhibition of HIV transcription: In T cells, IκBα has been shown to contribute to lower levels of LTR transcription and potentially contribute to latency. It is postulated that a similar mechanism of action could be in place for cells of the monocyte-macrophage lineage. In addition, NF-κB's association with the histone deacetylase inhibitor HDAC1 results in constriction of the chromatin so that RNA polymerase does not have access to its target DNA.