HIF1A and idiopathic pulmonary fibrosis: As a consequence, the scarring of lung tissue in IPF is reinforced by the expansion of fibroblast/myofibroblasts foci. Interestingly, HIF-1α and carbonic anhydrase IX (CAIX), a transmembrane protein expressed in hypoxic conditions, have been demonstrated to be upregulated in the lungs of IPF patients [11].