In addition, the principal component analysis (PCA) revealed a good separation of two CTRL patients out of three (CTRL1, CTRL3 green dots) with respect to IPF patients (Stage I and Stage II, orange and red dots respectively), while Stage I and Stage II patients subtype clustered almost together, also revealing that Stage I and Stage II patients (Component 3, 11.8%) share similar proteomic profile distribution (Figure 1D). Here, CTRL is linked to idiopathic pulmonary fibrosis.