IL21 and psoriasis: According to the proteomic analysis and immunohistochemical study, there is a definite connection between (1) mTOR (mechanistic target of rapamycin) protein (Table 2), (2) the cytokine expressions of TNF-α, Wnt, IL-1β, TGF-β, IL-6, IL-17, and IL-21 (Fig. 3), and (3) psoriasis pathogenesis; particularly proliferation and inflammation in relation to Th17 cell differentiation and mTOR signaling pathways, as shown in Fig. 5.