Galectin-3 binding protein, also known as MAC-2BP, M2BP, and 90K, is a secreted glycoprotein of the scavenger receptor cysteine-rich (SRCR) superfamily. Galectin-3BP binds Galectin-3 with high affinity, and additionally binds Galectins -1 and -7, several Collagen types, Fibronectin, beta 1 Integrins, and Nidogen. It is widely expressed in extracellular fluids and in pericellular areas of cell-rich tissues. Galectin-3BP dimers form linear and ring-shaped oligomers, most commonly decamers and dodecamers. It has been shown to stimulate natural killer cells and lymphokine-activated killer cell activity. Galectin-3BP upregulation has also been correlated with tumor aggressiveness.