Possible cellular targets and effects of gain-of-function c-kit mutations. In the BM microenvironment, a mutation in a common hematopoietic stem cell (HSC)/skeletal stem cell progenitor could affect both mast cells and the hematopoietic supportive stroma. Such a mutation might explain defects in bone, cartilage, or adipose tissue. Mutation in these cells, which arise from the common progenitor, might also disturb BM homeostasis.