Here we report that a chromosomal translocation, t(10;17)(q11.2;q23), juxta-poses the tk domain of the RET protooncogene, which resides on chromosome 10, to a 5' portion of the RIA gene on chromosome 17, leading to the formation of the chimeric transforming gene RET/PTC2.     ///    A t(10;17) translocation creates the RET/PTC2 chimeric transforming sequence in papillary thyroid carcinoma..     ///    "The tk domain of proto-RET can be fused either with the D10S170 gene generating the RET/PTC1 transforming sequence or with sequences belonging to the gene encoding the regulatory subunit RIA of c-AMP-dependent protein kinase A, thus forming the RET/PTC2 oncogene. "    ///    The finding of the transforming protein in primary tumor cell extracts supports the conclusion that RET/PTC2 activation plays a role in papillary thyroid tumorigenesis.. 