The flow cytometry results of the treated breast cancer cell lines demonstrated that chloroplast-made DARPin G3 from lyophilized leaves and chloroplasts bound to HER2-positive human breast cancer cells (SKBR-3), but did not bind to HER2-negative human breast adenocarcinoma cells (MDA-MB-231) (Fig. 4). The gene discussed is ERBB2; the disease is breast cancer.