Notwithstanding that the part of FKN in the lung fibrosis pathogenesis abides ambiguous, lung fibrosis induced by bleomycin in mice was correlated with upregulated expression of CX3CR1 on M2‐type macrophages and fibroblasts, which played a central part in fibrosis. The gene discussed is CX3CL1; the disease is pulmonary fibrosis.