Distinct multiple RET/PTC gene rearrangements in multifocal papillary thyroid neoplasia..     ///    "Multifocal disease, identified in 17 of the 21 patients, exhibited identical RET/PTC rearrangements within multiple tumors in only 2 patients. "    ///    "In clinically evident tumors, 47% had RET/PTC rearrangements. "    ///    "Of the 30 tumors (77%) positive for RET/PTC rearrangements, 12 were positive for RET/PTC-1, 3 for RET/ PTC-2, 6 for RET/PTC-3, and 9 for multiple RET/PTC oncogenes. "    ///    "Our results indicate that RET/PTC oncogene rearrangements may play a role in early-stage papillary thyroid carcinogenesis, but they seem to be less important in determining progression to clinically-evident disease. "    ///    "PCR products were resolved by gel electrophoresis, and Southern hybridization was performed with RET/PTC-1, -2, and -3 probes. "    ///    developed PC and to examine the diversity of RET/PTC in multifocal disease.     ///    "In multifocal disease, the diversity of RET/PTC profiles, in the majority of cases, suggests that individual tumors arise independently in a background of genetic or environmental susceptibility.. "    ///    "RT and PCR was performed using primers for RET/PTC-1, -2, and -3. "    ///    RET/PTC expression is highly prevalent in microcarcinoma and occurs more frequently than in clinically evident PC (P < 0.005).     ///    "We examined the expression of RET/PTC-1, -2, and -3 in human thyroid microcarcinomas and clinically evident PC to determine its role in early stage vs. "    ///    "Transgenic mice, expressing thyroid-targeted RET/PTC-1, develop PC. "