B78-D14  and B16-EpCAM  cells were grown in RPMI 1640 medium supplemented with 8.9% and 5%, respectively, fetal calf serum, 2 mM L-glutamine, 1 mM sodium pyruvate, and 1× nonessential amino acids. Further, 400 μg/ml G418 and 500 μg/ml Hygromycin B were added to B78-D14. Cells were extensively washed in PBS before application. The identity of the cell lines was regularly confirmed on the basis of cell morphology and the expression of the transgenes.