Because POSTN is an extracellular matrix protein that can be detected in the dermis of various skin inflammatory disorders including autoimmune disease such as scleroderma, pemphigus vulgaris, and bullous pemphigoid [17, 33], POSTN in melanoma might stimulate MDSCs to further produce chemokines such as CXCL5. Here, POSTN is linked to autoimmune disease.