CD28 and gastric cancer: 2.5 × 104 of CD8+ T cells from peripheral bloods of NC (n = 9), peripheral bloods of GC patients (n = 11), and tumor-residency of GC patients (n = 11) were cultured for 12 h in the presence of anti-CD3/CD28 with or without Pam3Csk4, a TLR2 agonist which was used for TLR2 activation.