T GF-β regulates many aspects of cellular performance relevant to tissue morphogenesis and homeostasis. Postnatal perturbation of TGF-β signaling contributes to the pathogenesis of many disease states, as recently exemplified through the study of Marfan syndrome (MFS), including aortic aneurysm and skeletal muscle myopathy. Heterogeneity in the regulation and consequences of TGF-β signaling, amplified in the context of disease, has engendered confusion and controversy regarding its utility as a therapeutic target. Three studies recently published in the JCI, including one in this issue, underscore the complexity of this subject. Heydemann and colleagues implicate dimorphic variation in latent TGF-β–binding protein 4 (LTBP4), a regulator of TGF-β bioavailability and activation, as a modifier of muscular dystrophy in γ-sarcoglycan–deficient mice. In contrast to experience with ascending aortic aneurysm in MFS, Wang and colleagues show that systemic abrogation of TGF-β signaling worsens (rather than attenuates) Ang II–induced abdominal aortic aneurysm progression in mice. Tieu and colleagues define alterations in the regulation of vascular inflammation in the pathogenesis of Ang II–induced aneurysm and dissection in mice, which may help shed some light on this apparent paradox.