CXCL12 and chronic myelogenous leukemia, BCR-ABL1 positive: Furthermore, bone marrow resident cells maintain CML LSCs by secreting various soluble factors such as Jagged 1 (a NOTCH ligand) [98], transforming growth factor (TGF)-β1 [99], bone morphogenic proteins (BMPs) [100], a chemokine, CXCL12 [101], IL-1 [102], and exosomes containing miR-126 [103].