Phaseolus vulgaris lectin (PHA-L) is affinity purified lectin made up of four subunits with carbohydrate specificity for complex oligosaccharides. PHA-L is known as leucoagglutinin and has high mitogenic and leucoagglutinating activity, and low erythroagglutinating activity. This lectin exhibits no agglutination with human erythrocytes. PHA-E differs from PHA-L in that the leucoagglutinin reacts strongly with Tamm-Horsfall glycoprotein and reacts weakly with porcine thyroglobulin. PHA-L binds to fetuin but does not precipitate the glycoprotein. This lectin is strongly inhibited by trisaccharide Gal Î²(1,4)GlcNAcÎ²(1,2)Man, and although this structure is present in many glycoproteins, PHA-L does not react with all of them. This lectin reacts strongly with certain carcinoma cell lines of high metastatic potential and has been proposed as a probable therapeutic agent. It has shown potential to inhibit graft vs. host reaction in transplantation studies and has also shown to promote the production of cytotoxic agents which could be useful in cancer therapy. Cy5, when bound to Phaseolus vulgaris Lectin (PHA-L), can show the binding pattern of this lectin in cellular imaging and flow cytometry. The excitation wavelength required for Cy5 to fluoresce is high enough to avoid overlap with most other fluorochromes, making it useful for dual-labeling experiments. Because of this high excitation, there is typically less background from autofluorescence of biological specimens.