Updated project metadata. Low serum levels or deficiency of 1α,25-dihydroxyvitamin D3 (VD3) are associated with a higher mortality in trauma patients with sepsis or acute respiratory distress syndrome, although the molecular mechanisms behind this observation are not yet understood. VD3 is known to stimulate lung maturity, alveolar type II cell differentiation and pulmonary surfactant synthesis. This study aims to expand the knowledge by quantitative characterization of NCI-H441 cells upon VD3 treatment at the proteome level.