CD8A and cancer: Since prior studies reported that T cells isolated from tumor-bearing mice and cancer patients have intrinsically diminished antigen responsiveness (Alexander et al., 1993; Jiang et al., 2015), we first established a relative baseline level of function for CD8+ OT-I T cells from tumor-bearing mice under in vitro conditions where access to antigen is L-selectin–independent (Figure 8A and B).