Griffonia Simplicifolia Lectin I Isolectin B4 (GSL I Isolectin B4) is a lectin, that can be isolated from the seeds of Griffonia simplicifolia. Griffonia Simplicifolia Lectin I Isolectin B4 recognizes and binds to carbohydrate structures with the sequence Galα1-4Gal, and can be used in biochemical and immunological.