We have created a three finger peptide able to target specifically the pl90BCR-ABL oncogene. The purpose of this project will be to develop a procedure in which the molecules that can interfere specifically with oncogene activity (ie. anti p190BCR-ABL peptide in our case) is co-introduced to the targeted cells (murine haematopoietic pro-B Ba/F3 cell lines expressing the pl90BCR-ABL oncogene and bone marrow cells derived from pl90BCR-ABL transgenic mice) via such vectors as viruses which encode a selectable cell surface expression marker (truncated human CD5 in our case). The targeted cells expressing the surface marker are completely separated from untargeted cells by sorting techniques for transfer back into the recipient. We hope that this gene therapy based approach will facilitate the development of a novel and curative treatment for Ph l-positive human leukaemias.