TGFBR1 and idiopathic pulmonary fibrosis: Here, we demonstrate, using clinically translatable pathophysiological readouts of IPF and associated PH that therapeutic treatment of bleomycin‐challenged rats with the ALK‐5 inhibitor SB‐525334 attenuated the decline in lung function that is clinically associated with a loss in normal lung architecture and reversed to near normal levels, the increase in mPAP associated with vascular remodeling.