AGO2 and idiopathic pulmonary fibrosis: However, upon lowering the anti-AGO2 antibody concentration (i.e. to 4 μg/ml), AGO2 protein expression was present in the same biopsies from both slowly progressive IPF and normal lung sections, but staining for this protein at this antibody dilution was absent in rapidly progressive biopsy sections (Figure 5 E–J).