**19. Hemagglutinin**

Soybean agglutinin (SBA) is a specific N-acetylgalactosamine-binding lectin that can aggluti‐ nate a number of cell types. SBA has potential for utilization as an affinity tag for high-quali‐ ty purification of tagged proteins, isolation of fetal cells from maternal blood for genetic screening, screening and treatment of breast cancer, and use as a carrier system for oral drug delivery. Tremblay et al employed transient and stable expression systems in potato and *Nicotiana benthamiana*, respectively, for the production of recombinant SBA, with the trans‐

genic protein accumulated to 0.3% and 4% of total soluble protein in potato tubers and *Nic‐ otiana benthamiana* leaves, respectively. Both rSBAs were able to resist degradation in simulated gastric and intestinal fluids. High yield and purity of rSBA can be obtained by af‐ finity column chromatography using N-acetylgalactosamine as a specific ligand [22].
