Based on this mechanistic link between efferocytosis and TGβ production, we hypothesized that persistent alveolar epithelial cell apoptosis, as occurs in lung fibrosis, might lead to protracted TGFβ expression as a result of ongoing ingestion of apoptotic cells by alveolar macrophages and that this macrophage response might translate into fibrosis rather than tissue homeostasis. Here, PPBP is linked to pulmonary fibrosis.