However, the combination of the two cytokines was able to downregulate the expression of the CDH1 gene that encodes E-cadherin and also reduced the expression of the genes associated with adhesion deficit, DDR1 and CCN3. Furthermore, MMP-9 is elevated in the skin and plasma of patients with common vitiligo, being produced in keratinocytes by the stimulation of TNFα and IFNγ and associated with E-cadherin cleavage.44 Here, DDR1 is linked to vitiligo.