Fig. (2) The Caveolin-1/CXCR4/CXCL12 Axis in Fibrosis. Profibrotic signals induce the differentiation in the bone marrow of a population of CD45+/CXCR4+/ColI+/caveolin-1 low cells that can be either CD14+ (filled circles) or CD14- (open circles). Under the influence of CXCL12, these cells traffic into the blood, then into damaged lung tissue where they begin to lose CD45 and to differentiate into myofibroblasts. CD45+/CXCR4+/ColI+/CD14- cells are fibrocytes, CD45+/CXCR4+/ColI+/CD14+ cells are referred to as collagen-producing monocytes [70].