In aggressive human and murine breast cancer cells, a biologically active 20-kDa peptide from the N-terminal domain of a2V (a2NTD) is proteolytically cleaved, secreted in the microvesicles and stimulates human peripheral blood mononuclear cells to produce IL-1β and IL-10 [16–18, 20–25]. Here, IL1B is linked to breast cancer.