PRF1 and psoriasis: Several of the identified genes (e.g., KLRC1, KLRD1, PRF1) also highlight the involvement of cytotoxic lymphocyte pathways in psoriasis–an avenue not directly addressed by current cytokine-centric therapies but evident in lesional inflammation (perforin-expressing cells are known to be enriched in psoriatic epidermis (Kastelan et al., 2004).