FN1 and type 1 diabetes mellitus: Furthermore, Western blotting revealed that collagen I (P < .01), collagen III (P < .01) and fibronectin (P < .01) were prominently up‐regulated in T1DM mice while markedly down‐regulated upon miR‐21 inhibition (collagen I, P < .01; collagen III, P < .01; fibronectin, P < .01) (Figure 3B).