1X10^6 unstimulated or anti-CD3/CD28 treated (2 days) BALB/C mouse splenocytes were surface stained with 0.2 ug APC Anti-Mouse PD-1/CD279 (APC-65142, Clone: RMP1-30), and 0.5 ug FITC Plus Anti-Mouse CD3 (17A2) (FITC-65077, Clone: 17A2). Cells were not fixed.