The met oncogene activated in vitro by treatment of a human osteogenic sarcoma (HOS) cell line with N-methyl-N’-nitronitrosoguanidine(MNNG) is related to the tyrosine kinase gene family. Probes from the met oncogene locus recognize two distinct transcripts of 9.0 kb and 10.0 kb which are independently expressed in a cell-type-specific fashion. While the met pmtooncogene locus expresses the 9.0 kb RNA and maps to human chromosome 7q21-31, the locus expressing the 10.0 kb RNA,(fpr; translocated promoter region) maps to human chromosome 1. Both MNNG-HOS cells and met NIH 3T3 transformants express a novel 5.0 kb RNA which represents a hybrid transcript with 5’sequences derived from fpr and 3’sequences from the met proto-oncogene. Treating HOS cells in vitro with MNNG, a known clastogenic carcinogen, resulted in fusion of two chromosomally disparate loci, met and tpr, generating the active met oncogene.