Figure 5: Autocrine TGF-� signaling is essential for the maintenance of a stem cell-like subpopulation. (A) Cells from exponential cultures of control and DNRII were plated in a 96-well low attachment plate at 1,000 cells/well with Mammocult medium. Representative images of the mammospheres formed by the two cell lines are presented. (B) The number of mammospheres in each well was counted after six days of culture. The data are presented as mean+SEM of 3 replicate wells (*p<0.05). (C) Cells from exponential cultures of the control and DNRII cells were harvested and cell extracts were used to detect the expression of ALDH1/2, CD29 and Notch1 by Western blotting. The density of each band was quantified with the Image J software and divided by the density of the corresponding GAPDH band. The ratio is presented under each blot after normalizing the values for the control as one unit.