IFNG and psoriasis: In order to verify whether this staining pattern was specific for C/EBPβ, we examined the expression patterns of additional epidermal transcriptional factors: RFX5, which is not usually overexpressed in lesional psoriatic skin, and STAT (Signal Transducers and Activators of Transcription) −1, a crucial mediator of IFN-γ signaling that has also been implicated in psoriasis pathogenesis.