In the establishment of BTcP model, we found that local injection of ET-1 at 18 μg/kg in the thigh of normal mice did not cause BTcP-like behaviors; however, local injection of the same concentration of ET-1 in the thigh of LLC tumor bearing mice even with good analgesic effect of morphine induced intense pain behaviors with dense production and synchronization of action potentials recorded by inserted electrodes in different segments of the spinal dorsal horn (data not shown). This evidence concerns the gene EDN1 and neoplasm.