The specificity and sensitivity of nested PCR were investigated in FIG-ROS1 positive U118MG cells in reconstitution experiments with peripheral blood mononuclear cells.     ///    "In conclusion, 14-16% of GBC and ECC were positive for FIG-ROS1. "    ///    "Formalin-fixed, paraffin-embedded tissues, derived from 65 Italian BTC patients, and six cell lines were analyzed by nested PCR to investigate the prevalence of a previously reported FIG-ROS1 fusion. "    ///    "We found that six out of 65 (9%) BTC patients were positive for the FIG-ROS1 fusion, comprising two out of 14 (14%) gallbladder carcinoma (GBC) patients and four out of 25 (16%) extrahepatic cholangiocarcinoma (ECC) patients. "    ///    "We developed a new, quick, specific, and sensitive PCR test to screen for the FIG-ROS1 fusion and applied it to a series of Italian patients with bile duct carcinoma (BTC). "    ///    None of the 26 intrahepatic cholangiocarcinoma cases harbored the FIG-ROS1 fusion.     ///    Screening for the FIG-ROS1 fusion in biliary tract carcinomas by nested PCR.. 