The concentration of HGF secreted by patient-derived bone marrow stem cells over 48 hr was reported to be 2–12 ng/mL (Takai et al., 1997) and the concentration of HGF was reported to be 0.5–11 ng/mL in pleural effusions from cancer patients (Eagles et al., 1996). This evidence concerns the gene HGF and Pleural effusion.