CXCR4 and leukemia: To test the significance of the CXCL12‐CXCR4 axis for parenchymal AML cells within the context of leukemia cell–niche interactions, we characterized the space explored before and after AMD3100 administration by analyzing the time‐averaged mean‐squared displacement of leukemia cell tracks, which indicates how far particle movement deviates from Brownian motion toward ballistic motion (Figure 3c).16 These two types of motion can be interpreted as indicators of an explorative/foraging (Brownian), versus environment‐agnostic (ballistic) behavior.