Increased expression of IL-6 and IL-6Rα in gp130^Y757F/Y757F mice correlates with STAT3 hyperactivation. Q-PCR analyses of (A) IL-6 and (B) IL-6Rα gene expression was performed on cDNA derived from total RNA prepared from thymocytes. Expression data from 3 samples per genotype are shown following normalization for 18S expression and are presented from replicate analysis as the mean fold induction ± SD relative to expression in gp130^+/+ samples. (C) Immunoblot analysis of IL-6Rα levels in lysates prepared from lymph node and thymus tissue. Densitometric quantitation of IL-6Rα in each of 2 representative samples per genotype was performed and normalized against ERK1/2, and data are presented as the mean fold induction ± SD relative to expression in gp130^+/+ samples. **P < .001 and *P < .05 versus expression in gp130^+/+ samples.