In psoriasis, keratinocytes produce a broad array of chemokines, including CCL2, CCL3, CCL5, CCL17, CCL20, CCL22, CCL27, CXCL1, CXCL8, CXCL9, CXCL10, CXCL11 and CXCL16 [31]. This evidence concerns the gene CXCL9 and psoriasis.