SPDL1 and neoplasm: The membrane-bound PD-L1 on the tumor cells was slightly correlated with the secretion of sPD-1 and sPD-L1 in the serum (Figure 2B), whereas no correlation between the membrane-bound PD-L1 on the splenocytes and sPD-1 or sPD-L1 was observed (Figure 2C).