Previous studies have shown that both co-stimulation and cytokines are critical for T-cell differentiation as T cells that receive initial activation through MHC peptide interaction with the TCR and co-stimulation from various receptors without receiving a third signal from various cytokines undergo poor proliferation and express lower levels of effector molecules47, which is consistent with the activation profile of TCRTAG cells delivered to untreated tumor-bearing mice. This evidence concerns the gene HLA-C and neoplasm.