Characterization of Brca1 cell lines by flow cytometry. Cell lines derived from anterior (A1.1 and A1.8) or posterior (P2.1 and P3.17) tumors were stained with fluorescently-conjugated antibodies against Cytokeratin 5 (A) or CD117 (B), in parallel with isotype control and analyzed by flow cytometry. In the histograms shown, the thick black line represents positive staining and the gray-filled lines represent the isotype control-matched mAb.