Flow cytometric and gene expression analysis of both monocytes and CD4+ T cells of patients treated with Tocilizmab revealed that there was a reduction in STAT3 phosphoyrylation and an attenuation in expression of STAT3-driven genes (37), demonstrating that IL-6 is a prominent inducer of this signaling cascade in human patients during GVHD. This evidence concerns the gene STAT3 and graft versus host disease.