The take rate in passage 1 varied from 20–100% among different tumor lines with marked differences in take rate between Brca1 null (TgK18GT121tg/+/Brca1Δ/Δ/p53Δ/Δ) and Brca1 wild type (TgK18GT121tg/+/p53Δ/Δ) tumors (95%±5.0 vs 64.5%±5.6, p<0.01). The gene discussed is BRCA1; the disease is neoplasm.