Accordingly, inducibility of RET oncogene rearrangements, i.e., the generation of the RET-PTC oncogene, specific for thyroid cancer, was investigated among human undifferentiated thyroid carcinoma cells (8505C), which do not have RET oncogene rearrangement, after 0, 10, 50, and 100 Gy of in vitro X-irradiation by means of reverse transcription polymerase chain reaction. 