Disclosed herein are inhibitors, such as antibodies, and antigen-binding portions thereof, that selectively bind complexes of LTBP1-TGFβ and/or LTBP3-TGFβ. The application also provides methods of use of these inhibitors for, for example, inhibiting TGFβ activation, and treating subjects suffering from TGFβ-related disorders, such as fibrotic conditions. Methods of selecting a context-dependent or context-independent isoform-specific TGFβ inhibitor for a subject in need thereof are also provided.
