PPBP and neoplasm: In turn, IL-6 induces the production of CXCL7 by MSCs [52], which has been shown to promote tumor invasiveness and metastasis in murine models [53, 54], as well as tumor growth through interaction with the tumor receptor CXCR2 [53] that, in turn, induces the synthesis of other cytokines including IL-6 and IL-8.