Examination of pleural fluid, patient-derived tumor cells and tumor cell lines are invaluable in evaluating the “secretome.” The mesothelioma secretome includes the chemokines CCL2, CCL4, CXCL10, CXCL5, CXCL1, and CXCL12, the cytokines IL-10 and IL-6, and the growth factors TGFβ, VEGF, MCSF, GM-CSF, G-CSF, FGF, and PDGF (33, 37, 48–53). The gene discussed is CCL4; the disease is mesothelioma.