ABL1 and myeloproliferative disorder: Although these studies established that BCR-ABL in such a system can cause myeloproliferative disease in mice, in these initial models more than one type of disease developed, whereas the leukemic phenotype observed was also dependent on how donor mice were conditioned, suggesting that the target cell in which BCR-ABL was expressed, and additional mutations in those cells, was important in determining the disease burden [41].