AR and benign prostatic hyperplasia: To determine the potentially different roles for stromal AR in macrophage-induced stromal cell growth between TZ and PZ, we established an in vitro co-culture system of macrophages/prostate stromal cells from TZ and PZ of BPH patients; and we assert that our co-culture model can mimic the in vivo interaction of macrophages and stromal cells in the inflammatory microenvironment found within the human prostate in BPH.