Figure 2

Mouse luminal progenitors have multilineage differentiation potential but a rare mammary repopulating unit potential. (A) Double-sorted oestrogen receptor-negative (ER^-) progenitors, oestrogen receptor-positive (ER⁺) progenitors and nonclonogenic luminal (NCL) ER⁺ cells were injected at the indicated numbers into cleared fat pads and the mammary repopulating unit (MRU) frequency and distribution in each subpopulation was determined. *Basal MRU frequency is from Prater MD, Petit V, Russell IA, Giraddi R, Menon S, Schulte R, Deugnier M-A, Glukhova MA and Stingl J (manuscript submitted). (B) Representative whole mounts of outgrowths derived from the different luminal cell populations (upper panels). Representative primary outgrowths of H & E and immunostained sections to detect luminal (GATA3 and MUC1) and basal (K5 and p63) cells (lower panels). Scale bar = 100 μm and 10 μm, respectively. (C) Phenotype of colonies generated when ER^- and ER⁺ progenitors are cultured in Matrigel. Scale bar = 10 μm.