Although the function of the autonomic nervous system (ANS) in mediating the 
flight-or-fight response was recognized decades ago, the crucial role of 
peripheral innervation in regulating cell behavior and response to the 
microenvironment has only recently emerged. In the hematopoietic system, the ANS 
regulates stem cell niche homeostasis and regeneration and fine-tunes the 
inflammatory response. Additionally, emerging data suggest that cancer cells 
take advantage of innervating neural circuitry to promote their progression. 
These new discoveries outline the need to redesign therapeutic strategies to 
target this underappreciated stromal constituent. Here, we review the importance 
of neural signaling in hematopoietic homeostasis, inflammation, and cancer.