ERBB2 and breast cancer: Similarly, cell-based ELISA studies on immobilised confluent HER2-positive human breast cancer cells (SKBR3) showed higher responses with the Herceptin, antihuman IgGFc-biotin, and streptavidin peroxidase combination compared with the biotinylated-Herceptin and streptavidin peroxidase combination (open and closed triangles, respectively, in Figure 1(b)).