A chromosomal translocation uniquely associated with chronic myeloid leukemia leads to the formation of a chimeric gene, bcr-abl, on the Philadelphia chromosome. The BRC-ABL protein displays an uncontrolled tyrosine kinase activity similar to that seen with the transforming oncogene of the Abelson murine leukemia (ABL) virus (v-abl). An interleukin 3 dependent cell line, IC.DP, has been transfected with a gene encoding a temperature sensitive v-ABL. In the absence of interleukin 3 at the restrictive temperature for ABL tyrosine kinase activity IC.DP cells died via apoptosis. At the permissive temperature ABL tyrosine kinase activity promoted IC.DP cell survival but not proliferation. ABL therefore can specifically suppress apoptosis.