Thus myofibroblast differentiation and fibroblast senescence may form part of a dynamic spectrum of fibroblast responses found at different stages along the same regulatory program, and it is possible that the pathological accumulation of SMA-positive, ECM-producing myofibroblasts in cancers and progressive fibrosis may result from an ongoing process of senescence evasion or continuous myofibroblast repopulation. The gene discussed is SMN1; the disease is cancer.