IL17A and psoriasis: Consistent with its mechanism of action, ustekinumab improved disease-associated genes that were modulated by IL-23, including IL-17A and the pathogenic psoriasis molecular signature genes that were induced in keratinocytes by IL-17 receptor signaling1,2,22 (Figure 3B; eFigure 3C in Supplement 2; eTable 7 in Supplement 4).