A significant positive correlation between expression of Osr1 with prostatic stem/progenitor cell markers including Itga6, Ly6a and Tacstd213, as well as Psca14, a prostate cancer stem cell marker, (Spearman r = 0.3, 0.31, 0.4, and 0.41, respectively), was identified in urogenital sinus epithelium (UGE) but not urogenital sinus mesenchyme (UGM) cells (Fig. 1d vs. Supplementary Fig. 2f), suggesting the progenitor properties of Osr1-lineage cells in prostatic epithelial development. Here, LY6S is linked to prostate cancer.