Apparently, upregulation of type IV collagen in lungs is more specific for the initial stages of fibrotic process: recent proteome analysis demonstrated, in agreement with our findings, strong upregulation of COL4A1 in the latest stage of asthma in mice [78], and Urushiyama et al. showed massive production of type IV collagen by α-SMA-positive myofibroblasts during early fibrotic lesions of idiopathic interstitial pneumonias in humans [79]. Here, COL4A1 is linked to idiopathic interstitial pneumonia.