CASP3 and idiopathic pulmonary fibrosis: To determine whether the reduced MMP-8 staining in ATII cells in IPF lungs is linked to increased rates of ATII cell apoptosis which has been reported in IPF lungs [28], [29], we double immunostained IPF versus normal lungs for a marker of apoptosis (active caspase-3) and a marker of ATII cells (surfactant protein C; SP-C).