FN1 and psoriasis: Although studies have demonstrated that the inflammatory cytokines IL-1β, TNF-α, IL-17 and IL-23 play key roles in the skin lesions and inflammation in psoriasis, extracellular matrix molecules (ECM), such as extradomain A+ fibronectin, also promote the skin lesion in psoriasis32, 33, 34, 35, indicating that not only IL-1β, TNF-α, IL-17 and IL-23 but also ECM proteins contribute to the pathogenesis and development of psoriasis by up-regulating inflammatory cytokine production.