Different cytokines activate STAT3 in primary and IL-2–expanded NK cells. (A) NK cells were MACS-purified, FACS-sorted, and stimulated with IL-2 alone or together with IL-6 (+IL6Rα), IL-10, IL-12, IL-15, IL-18, IL-21, IL-23, or IFN-β for 20 minutes. Western blot analysis show levels of pSTAT3-Y705 and STAT3. β-actin was detected as loading control. (B) IL-2–expanded NK cells were stimulated with indicated cytokines for 20 or 200 minutes. Western blots show levels of pSTAT3-Y705 and STAT3. β-actin was used as loading control. (C) Lamina propria cells from the colon or small intestine of Stat3^fl/fland Stat3^Δ/ΔNcr1-iCreTg mice. Cells were stimulated with IL-23, fixed, and permeabilized, and IL-22 production of CD45⁺CD3⁻CD19⁻NKp46⁺ cells was analyzed by flow cytometry.