Lysis of cancer cells endogenously expressing MUC1 by CTL.M1.1 (A) and CTL.M1.2 (B). Human breast cancer cell line MCF-7 (HLA-A2⁺/MUC1⁺), ovarian cancer cell line SK-OV-3 (HLA-A2⁻/MUC1⁺), and the immortalized B-cell line Croft (HLA-A2⁺/MUC1⁻) were used as targets in a stardard ⁵¹Cr-release assay. Croft cells were pulsed with the MUC1 peptides or an irrelevant Her-2/neu–derived peptide E75. (▪) Croft + E75 peptide; (□) Croft + M1.1 peptide; (•) MCF-7; (▵) SK-OV-3.