Suppression of PI3K activation by PDGFRβ prevents the Marfan-like phenotypic changes in the vascular wall in the presence of unabated TGFβ signaling, suggesting a pivotal role of LRP1-controlled and PDGFRβ-dependent PI3K activation in the pathogenesis of Marfan syndrome. The gene discussed is LRP1; the disease is Marfan syndrome.