CXCR4 and ovarian cancer: A former study indicated that the tumor-associated inflammatory mediator PGE2 attracts myeloid derived suppressor cells (MDSCs) into ascites of ovarian cancer patients, a process dependent on the expression of C-X-C chemokine receptor type 4 (CXCR4) and its ligand CXCL12 in the ascites microenvironment (Obermajer et al., 2011).