CXCL12 and neoplasm: MSC recruitment to tumor sites is facilitated through numerous factors secreted by stroma, including growth and angiogenic factors (PDGF, FGF, VEGF, SDF, HGF), chemokines, and inflammatory cytokines (CCL2, CCL5, CCL22 and CXCL12, TNFα, TGFβ, IL-1β, IL-6, IL-8) [91,93].