To evaluate the ability of the chimeric protein 4LB5-HP-RNase to bind to NCL-positive cells, we carried out an ELISA assay on a panel of breast tumor cells, such as MDA-MB-231, MDA-MB-436, BT-549 (all Triple-Negative Breast Cancer cells) and MCF7 cells (luminal epithelial breast cancer), expressing high levels of surface-NCL. The gene discussed is HP; the disease is breast cancer.