Moreover, the validation of genes regulating pulmonary fibrosis of non-allergic etiology (bleomycin-induced lung fibrosis) on asthmatic and asthma-driven fibrotic lungs allows us to identify new promising universal genes (Col4a1 and Col4a2) involved in the development of pulmonary fibrosis regardless of its etiology. The gene discussed is COL4A2; the disease is asthma.