Despite recent studies demonstrating that IL-23/IL-17 axis has a pathogenic role in the development of psoriasis, IFN-γ remains a crucial cytokine trigger of resident skin cells, as it potently enhances the expression of pro-inflammatory genes in epidermal keratinocytes activated by the transcription factor STAT1 and alters their apoptotic/growth rate. The gene discussed is IL17A; the disease is psoriasis.