SMAD1 and glaucoma: However, Smad6 is a negative regulator that interferes with the phosphorylation of Smad1 and Smad2 and disturbs the formation of the heteromer.41 Smad6 has anti‐fibrotic effects in conjunctival fibroblasts and a mouse model of glaucoma filtration surgery, and overexpression of Smad6 attenuates TGF‐β‐induced collagen production.22 CCN5 is one of the connective tissue growth factor/cysteine‐rich 61/nephroblastoma overexpressed (CCN) family that has been shown to play important roles in many processes, including adhesion, extracellular matrix regulation, proliferation, migration.