We have isolated a human genomic DNA (designated human frt) cross-hybridizing with the v-ros oncogene of UR2 sarcoma virus. Sequencing analysis of this fragment revealed that this sequence contains a 123-base-pair exon-like structure surrounded by consensus sequences of splice acceptor and donor sites. The deduced amino acid sequence of this stretch was highly homologous to a portion of a tyrosine kinase domain of src family. The human frt sequence was found to be conserved in a wide variety of vertebrates. By using a human-mouse hybridoma panel, human frt was located on chromosome 13, while human c-ros-1 was located on chromosome 6.