GAL and melanoma: Potential explanations for these differences could be that (1) the F4/80+ and CD68+ macrophages represent distinct populations that are regulated differently by Gal1, (2) glioma and melanoma respond in distinct ways to reduced levels of Gal1 or that (3) neutralization of circulating Gal1 by antibodies generates a different response in the tumor microenvironment compared to knockdown of Gal1 in the tumor cells.