To test binding of the six antibody fusion proteins to ErbB2 via their scFv(FRP5) domain and recognition of the incorporated E5B9 epitope peptides by UniCARs 5B9.z and 5B9.28.z, ErbB2-positive MDA-MB-453 breast carcinoma cells (Supplementary Fig. 2), and UniCAR-expressing NK-92/5B9.z and NK-92/5B9.28.z cells were incubated with the purified target modules, and surface binding was analyzed by flow cytometry. Here, ERBB2 is linked to breast carcinoma.