Method for treating and diagnosing disease using inhibitors of goodpasture antigen binding protein

A method for treating pulmonary fibrosis (PF), comprising administering to a subject in need thereof an effective amount of an inhibitor of 77 kD GPBP to treat the PF, wherein the GPBP inhibitor is a compound of formula (I):

• or a pharmaceutically acceptable salt thereof, wherein:
• R is CR5;
• R5 is selected from the group consisting of hydrogen, halogen, cyano, nitro, hydroxy, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, halo(C1-C6 alkyl), C1-C6 alkoxy, halo(C1-C6 alkoxy), amino, (C1-C6 alkyl)amino, di(C1-C6 alkyl)amino, hydroxy(C1-C6 alkyl), (C1-C6 alkoxy)C1-C6 alkyl, and amino(C1-C6 alkyl);
• R1 is hydrogen;
• R2 is C1-C6 alkyl or hydroxy(C1-C6 alkyl);
• R3 is —(CH2)1-2—C(O)OH or —CH═CH—C(O)OH;
• and
• R4 is C1-C6 alkoxy.