Galectin 8 (GAL8), also known as prostate carcinoma tumor antigen 1 (PCTA1) in human, is a tandem repeat-type galectin. is a member of the lectin family, of which 14 mammalian galectins have been identified. It is also a member of the beta-galactoside-binding protein family that plays an important role in cell-cell adhesion, cell-matrix interactions, macrophage activation, angiogenesis, metastasis, apoptosis. In this case, we chose rabbit erythrocyte (RaE) to assay its ability of agglutination. A general procedure for hemagglutination assay (or haemagglutination assay; HA) is as follows, two-fold dilute the recombinant Rat GAL8 with 0.9% sodium chloride injection, add 50μL a serial dilution of GAL8 to each well of a U or V-bottom shaped 96-well microtiter plate. The final well serves as a negative control with no GAL8, replace with 50μL 0.9% sodium chloride injection. Then add 50μL 1% rabbit erythrocyte to each well and mixed gently. The plate is incubated for 3 hours at room temperature. The results are shown in Figure 1. It was obvious that the minimal effective concentration of GAL8 is 1.5625 μg/mL.