Given that scFv L4 displayed high sensitivity and specificity in recognizing the native form of nectin-4 on breast cancer cell monolayer and tissue sections (Figures 4, 5) and its ability to prevent nectin-4-positive tumor cell cluster formation (Figure 6), the scFv and its derivatives may be further developed and investigated for their diagnostic and therapeutic values. The gene discussed is NECTIN4; the disease is neoplasm.