Of these mediators, PGE2, tumor necrosis factor-α (TNFα), nerve growth factor (NGF), Regulated on Activation Normal T cell Expressed and Secreted (RANTES, also known as C-C chemokine ligand 5: CCL5), and interleukin (IL) IL-8 and IL-1β are all elevated within the peritoneal fluid of endometriosis patients who reported CPP pain (Ryan et al., 1995; Barcz et al., 2000; Bedaiwy et al., 2002; Scholl et al., 2009). The gene discussed is CCL5; the disease is endometriosis.