LGALS1 and neoplasm: The formation of a complex between the produced ligand, i.e., the pentasaccharide of ganglioside GM1, and the lectin, i.e., the homodimeric galectin-1, is the molecular trigger for a signaling cascade, which results in the final response (growth/activity inhibition, setting limits to tumor cell proliferation and T cell-mediated activity causing auto-immune diseases).