OAS2 and psoriasis: OAS2 was expressed significantly higher in psoriatic-lesional (Pso-L) epidermis when compared with peri-lesional (Pso-PL), non-lesional (Pso-NL) and healthy controls (Figure 4A), and the localization of OAS2 was mainly in keratinocytes, indicating that keratinocytes may be a major source of OAS2 production in psoriasis.