SEMA4D and breast carcinoma: SEMA4D is known to promote differentiation of alternatively activated macrophages, while anti-SEMA4D treatment increases the population of classically activated macrophages in mammary carcinoma tissue, and induces the production of inflammatory cytokines.27,28 This is in line with our finding of SEMA4D down-regulation in macrophages, considering GM-CSF stimulation is a model of monocyte-to-classical macrophage differentiation.