Figure 2. P4 shifts breast cancer cells towards a more CK5⁺ and CD44⁺ phenotype.

K5pGFP cells were treated with vehicle (EtOH) or 100 nM P4 (T47D^K5pGFP), or 10 nM E2 + 100 nM P4 (MCF7^K5pGFP) for 24 h. Cells were either unlabeled (A, B upper panel) or labeled with an Alexa Fluor 647 conjugated antibody to CD44 (A, B lower panel) and analyzed by flow cytometry. Dead cells were omitted via addition of 10 nM DAPI and gates were drawn based on vehicle-treated samples. The percent of cells in each quadrant is indicated. C. T47D-PR^null cells were treated with vehicle (EtOH) or 100 nM P4 and analyzed by flow cytometry as in panel A.