Affinity purified Vicia villosa lectin or agglutinin (VVL/VVA) is a tetramer composed of four subunits. VVL consists of A and B subunits, with a dominant isolectin that appears to be B subunit-rich. A4 isolectin agglutinates specifically A1 erythrocytes. B4 isolectin does not agglutinate A, B, or O-erythrocytes; however, B4 binds the Tn antigen, a molecule expressed on the surface of most tumor cells. A2B2 and similar tetramer isolectins display properties characteristic of both A4 and B4 isolections.Texas Red is a red-fluorescent dye and when bound to Vicia villosa Lectin (VVL/VVA) can show the binding pattern of this lectin in cellular imaging applications. There is very little overlap between the emission spectra of Texas Red and FITC making this combination ideal for dual-labeling experiments. Rhodamine dyes, such as Texas Red, are more photostable and less sensitive to pH change when compared to other dyes such as fluorescein.