Previous biomarker studies in IPF have focused more on measuring levels of proteins that predict prognosis rather than measuring proteins whose levels are predictive of specific pathologic processes; examples include surfactant protein-A and-D (SP-A and SP-D), [24-26] MMP7, [27,28] and Krebs von den Lungen 6 antigen (KL-6), [29,30]. This evidence concerns the gene FASLG and idiopathic pulmonary fibrosis.