Figure 5. CircPlek/miR-135b-5p/TGF-βR1 axis affects the activation of TGF-β/Smad signaling pathway. (A) Fluorescence assays were performed to detect the location of CircPlek in spinal fibroblasts. Red represents CircPlek staining and blue represents nuclear DNA staining by DAPI. (B–C) Western blot analysis of the protein levels of Smad2, Smad3, p-Smad2, and p-Smad3 in spinal fibroblasts transfected with miR-135b-5p mimics (B) or siCircPlek (C). (D) After co-transfection of spinal fibroblasts with siCircPlek and an miR-135b-5p inhibitor with or without SCI, Smad2, Smad3, p-Smad2, and p-Smad3 protein levels were measured using western blotting.