In the breast cancer stroma, the action of DDR2 in cancer associated fibroblasts (CAFs) is particularly important for force-mediated remodeling of collagen fibers in the tumor extracellular matrix (ECM), thereby controlling the mechanical properties (e.g. stiffness) of the breast tumor stroma (Zhang et al., 2016; Bayer et al., 2019). The gene discussed is DDR2; the disease is cancer.