In IPF patients, macrophages‐derived MMP8 and MMP28 are increased.[63, 64] In radiation‐induced pulmonary fibrosis, senescent macrophage‐derived Mmp2, Mmp9, and Mmp12 are also increased, which might trigger fibrotic phenotype transition in fibroblasts.[37] Further, macrophage‐derived MMP12 causes endothelial dysfunction, including the decrease of viability, migration, and trans‐endothelial resistance.[65] Further investigation is required to elucidate the underlying mechanisms by which MMPs function as a mediator of cell‐to‐cell communication in fibrosis. The gene discussed is MMP12; the disease is fibrosis.