Expression of cancer stem/progenitor cell-like marker proteins in 10AT-Her2 and 10AT-Neo cells. (A) Cultured HER2-expressing 10AT-Her2 cells and empty vector transfected 10AT-Neo control cells were treated with or without 200 μM I3C for 48 hours. Production of HER2, CD44, CD24, ALDH-1, nucleostemin (NS) and actin protein were determined by Western blot analysis of electrophoretically fractionated total cell extracts. (B) Cell surface expression of CD44 and CD24 in 10AT-Her2 cells and 10AT-Neo cells was quantified by flow cytometry of 500,000 cells in triplicate independent cell cultures. (C) ALDH-1 activity was quantified in 10AT-Her2 and 10AT-Neo cells by ALDEFLUOR assay as described in the Methods section. ALDH-1, aldehyde dehydrogenase-1; HER2, human epidermal growth factor receptor-2; NS, nucleostemin.