RelB, also known as I-Rel, is a member of the Rel transcription factor family which also include; RelA-p65, c-Rel, NF-kB1 p100/52 and NF-kB2 p105/50. Unlike other Rel-related protein, RelB does not bind to DNA or to inhibitor IkB, but is instead sequestered in the cytoplasm by precursor p100. Once p100 is processed, the p52/RelB complex translocates into the nucleus. RelB is also the transcription factor that has been associated most directly with dendritic cells (DCs) differentiation and function. It is upregulated and translocated into the nuclei of DC in response to various stimuli. RelB is also essential for generating a specific DC subset (CD11c +/CD11b +/CD8 -/Dec205 -) from hematopoietic stem cells.