Whenever sugars are mentioned in relation to health and disease, it is in the context of metabolism and gaining calories. However, sugars have many other functions in our physiology and are found on cell surfaces and in extracellular matrix (ECM), forming an integral part of tissue microenvironment. Here they bind to their partner ligands, known as lectins, forming lectin-sugar interactions that have been known to play important roles in physiological and pathological contexts. In an article published and featured on the cover of Proceedings of the National Academy of Science (PNAS) last week, the laboratory of Distinguished Scientist Mina Bissell in the Biological Systems and Engineering Division of Lawrence Berkeley National Laboratory (Berkeley Lab), in collaboration with the research group of Professor Carolyn Bertozzi, now at the Stanford University Department of Chemistry, report exciting data and new insights into the roles a lectin, Galectin-1 (Gal-1), plays in mammary gland branching morphogenesis. This work also sheds some light on breast cancer progression.