N-cadherin regulates osteoblasts but not HSCs. (A) The initial observation of the osteoblastic niche suggested a model in which N-cadherin was expressed by both spindle-shaped osteoblasts and hematopoietic stem cells (HSCs). Homotypic adhesion between N-cadherin expressed by osteoblasts and N-cadherin expressed by HSCs enables HSC anchoring in the niches and signals quiescence and self-renewal to HSCs. (B) In the new model, N-cadherin is only expressed by osteoblasts, not by HSCs. Deletion of N-cadherin in osteoblasts alters osteoblast function and maturation but has no effect on HSC behavior.