STAT3 and psoriasis: Transgenic mouse models manipulating specific immunological molecular components help to unravel the pathomechanisms of psoriasis further, suggesting that the observed hyperproliferation of keratinocytes is mediated via the altered regulation of transcription factor signal transducers and activators of transcription 3 (STAT3; [46,63,64]), as well as an aberrant T-cell function [46].