CTLA4 and neoplasm: To overcome the CCK-8 assay limitation where the percentage of cell viability reflected both the proliferation of CIK cells and tumor cells (Figure 6A and Figure 7A), we labeled the CIK cells with CellTraceTM violet and conducted flow cytometry experiments to observe the effect of anti-PD-1 and anti-CTLA-4 antibodies on the proliferation of CIK cells in the absence and presence of tumor cells.