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. This evidence concerns the gene NECTIN4 and breast cancer.