IGFBP3 and neoplasm: To investigate the effect of IGFBP3 regulated PD-L1 expression on T cells viability, we established a co-culture system of tumor cells with Jurkat cells that had been activated with phorbol 12 myristate 13 acetate (PMA, 20 ng/ml) and ionomycin (500 ng/ml) for 12 h at a ratio of 4:1 (T cells: tumor cells) for 24 h in vitro.