Galectin-1 is a member of the beta-galactoside-binding family and is a dimeric protein of 14kD participating in a variety of normal and pathological processes, including cancer progression. Galectin-1 can affect the proliferation of normal and malignant cells. Inhibition of cell growth is observed in a lactose-dependent manner as lower concentrations of the lectin stimulate cell proliferation. Galectin-1 may also be implicated in the induction of apoptosis of activated T cells through the binding of exogenous galectin-1 to CD45 molecules present on the surface of lymphocytes. Galectin-1, reported to be present either at the surface of cancer cells or accumulated around these cells could act as an immunological shield to protect against a T cell immune response and provide an advantage for survival.