Mouse splenocytes unstimulated (left) or stimulated overnight with Mouse IL-15/IL-15R Complex Recombinant Protein Carrier-Free (Product # 34-8152-82) (right) were stained with Anti-Mouse NK1-1 PE-Cy7 (Product # 25-5941-82) and 0.125 µg of Anti-Mouse E4BP4 (NFIL3) PE. Intracellular staining for E4BP4 was performed using the Foxp3 Staining Buffer Set (Product # 00-5523-00) and protocol. Cells in the lymphocyte gate were used for analysis.