To assess the relevance to human lung fibrosis of the cellular and animal models of liver fibrosis, we analyzed, in preliminary studies, the role of activated RSK and phosphorylated C/EBPβ on Thr266 (identical to mouse Thr217 phosphoacceptor) as possible mechanisms leading to increased lung fibrosis in two patients with severe idiopathic lung fibrosis. Here, CEBPB is linked to pulmonary fibrosis.