Soluble Fas-L (sFas-L), increased in the sera of LGL leukemia patients, especially those with CD8+CD16+CD56− LGLs and STAT3 hyperactivation, functions as a decoy receptor preventing Fas-mediated apoptosis [38,44,45,46]. The gene discussed is FASLG; the disease is T-cell large granular lymphocyte leukemia.