StemReginin 1 is an aryl hydrocarbon receptor (AHR) antagonist (IC50 = 127 nM). StemReginin 1 exhibits no inhibitory activity against a panel of 61 kinases and preferentially inhibits human AHR. StemRegenin 1 induces CD34+ cell expansion by binding and antagonizing AhR. It is reported to promote the self-renewal of human hematopoietic stem cells in culture by sustaining the cellular expression of CD34. StemRegenin 1 also promotes human plasmacytoid and myeloid dendritic cell development from CD34+ hematopoietic progenitor cells. The product also promotes expansion of human promyelocytic leukemia cell line NB4.