CCL19 and acute lymphoblastic leukemia: Notably, in pre-clinical in vivo T-ALL models generated by overexpression of the intracellular cleaved form of Notch1 (ICN1), CCR7 overexpression led to enhanced chemotaxis and invasion into different tissues, especially to leptomeningeal spaces of brain and spinal cord, in which endothelial cells were shown to produce CCL19 (25).