TLR2 and neoplasm: Specifically, BCa cell-derived exosomes can stimulate NF-кB activation in macrophages, resulting in secretion of diverse cytokines including IL-6, TNF-α, G-CSF and CCL2, while genetic depletion of Toll-like receptor 2 (TLR2) or MyD88, a critical signaling adaptor of the NF-кB pathway, completely abrogates the effect of tumor-derived exosomes [97].