A point mutation in the Kit PTK (D816V) is associated with transformation in mast cell leukaemia [2] and in the myeloproliferative disorders the t(9;22) translocation found within Chronic Myeloid Leukaemia (CML) leads to the production of the BCR/ABL oncogenic PTK [3]. This evidence concerns the gene PTK2B and mast cell leukemia.