Serum ratios of IGF-1:IGFBP-1 (p < 0.01), IGF-1:IGFBP-2 (p < 0.0001), IGF-2:IGFBP-1 (p < 0.05) and IGF-2:IGFBP-2 (p < 0.0001) were significantly lower in the not treated IPF group than in healthy subjects (Table 2). Here, IGFBP1 is linked to idiopathic pulmonary fibrosis.