The microenvironment influences gene expression so that the behavior of a cell is largely
determined by its interactions with the extracellular matrix, neighboring cells, and soluble
local and systemic cues. We describe the essential roles of context and organ structure in
directing mammary gland development and differentiated function and in determining the
response to oncogenic insults, including mutations. We expand on the concept of “dynamic
reciprocity” to present an integrated view of development, cancer, and aging and posit that …