Reactivity of the recombinant antibodies with cell lines by the use of flow cytometry. The recombinant antibodies stain the cell surface of cell lines HEK293T, MIN6, and T-47D (panels A-F). Dotted lines represent specific staining with the recombinant antibodies, whereas continuous lines represent staining with a negative control mouse Igγ2b Fc fragment. Trypsin treatment reduces specific surface antibody binding (dashed line, panel G). Incubation of the cell lines with antibody diluted in fetal bovine serum reduces specific antibody binding as demonstrated in 2 of the cell lines (dashed line, panels H and J).