Elimination of mammary carcinoma cells during ex vivo culture in the presence of IT. (A) The 7-day time point of a 1:10 mixture of MDA-MB-453 breast cancer cells and CD34⁺progenitor cells as shown in Fig 4A was immunostained with anticytokeratin antibodies and photographed at 100× magnification. Anti–Erb-B2 IT was present in the cultures at the indicated concentrations. (B) Tumor cells from patient no. 5 (Table 2) were cultured in α-MEM/10% FCS without (control) and with 1,000 ng/mL anti–EGF receptor (EGFR) IT for 7 days. Cells were fixed on glass slides, stained with anticytokeratin antibodies, and photographed at identical (1,000×) magnification.