Acute lung injury (ALI) is a multidimensional entity characterized by key pathophysiologic features that the American Thoracic Society has categorized into four domains, which include 1) histological evidence of tissue injury, 2) alterations of the alveolar-capillary barrier, 3) presence of an inflammatory response, and 4) physiologic dysfunction.(52) First, our studies looked for differences in histologic injury and permeability of the alveolar-capillary barrier between Col1a2/Vcan−/− and WT mice. The gene discussed is COL1A2; the disease is acute lung injury.