Isolectin B4 (IB4) is one of a family of five alpha-D-galactose-binding lectins from Griffonia (Bandeiraea) simplicifolia. These isolectins are tetromeric structures, consisting of various combinations of A and B subunits. IB4 has been used to label primary sensory afferent terminals in the rat dorsal horn, inhibit ascites tumor cell growth, label small-diameter trigeminal ganglion neurons, as well as agglutinate B-type red blood cells.