INPP4A and idiopathic pulmonary fibrosis: Therefore, we looked into finer resolution, that is, the fibroblastic foci (FF), which are regions of active fibrogenesis in IPF (Katzenstein & Myers, 1998) and hypothesized that the increase in INPP4A expression in IPF lungs must be reflected by the increase in INPP4A expression in the pathological core of pulmonary fibrosis, the fibroblastic foci.