Updated project metadata. Haematopoietic stem cells (HSC) reside in locations within the bone marrow microenvironment (BMM) featuring a slightly higher extracellular calcium ion concentration [eCa2+]. HSC respond to [eCa2+] via the G-protein coupled calcium-sensing receptor (CaSR), but the role of CaSR for leukaemia and leukaemia stem cells (LSC), the malignant counterpart to HSC, is poorly defined. Here we performed a proteomic analysis on Lin- MLL AF9+ cells, comparing WT cells to cells lacking CaSR using TMT-based proteomics.