B3GAT1 and neoplasm: Of note, during this 4-day period, no strong CD57 expression was detected on the T cells when they had been preincubated with CD57– AC133+ tumor cells (Figure 2B, bottom panels); it is therefore unlikely that the high CD57 expression level on the T cells during the 4-day period following incubation with the CD57+ tumor cells was due to endogenous expression by the T cells.