To identify the contribution of CaSR to leukaemia progression, we transplanted 5-fluorouracil (5-FU)-pre-treated (for AML and CML) or non-5-FU-pre-treated (for B-ALL) wildtype (Mx1-Cre-ER−/− CaSR flox/flox; WT) or Casr KO (Mx1-Cre-ER−/+ CaSR flox/flox) donor BM into WT mice (Mx1-Cre-ER−/− CaSR flox/flox) using the retroviral transduction/transplantation models of MLL-AF9-driven AML, BCR-ABL1-induced CML or BCR-ABL1+ B-ALL14. The gene discussed is CASR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.