The zebrafish (Danio rerio) is a potentially exquisite model system to investigate the genetic basis of cancer, but it has proved difficult to create stable transgenic lines of tumor-bearing fish. In the February 7 Science, David Langenau and colleagues report the generation of a zebrafish model of T cell leukemia that highlights the potential application of using fish to find cures for cancer (Science, 299:887-890, February 7, 2003).

Langenau et al. created transgenic zebrafish expressing the mouse c-myc oncogene, or a fluorescent GFP-Myc fusion, under the control of the zebrafish Rag2 promoter. The fish developed tumors by the age of seven weeks. The GFP fluorescence enabled monitoring of tumor formation and spreading in the translucent fish. The clonal T cell leukemias first appeared in the thymus and then spread to gills, fins and retro-orbital soft tissue. They demonstrated the transplantability of the...