Evidence has shown that ZEB1, a well-known EMT activator, induces PD-L1 expression in tumor cells by relieving the miR-200 (a suppressor of EMT that targets PD-L1, a ligand for the CTL checkpoint receptor PD-1)-mediated suppression of PD-L1, resulting in the suppression of CTL function and promotion of metastasis [34]. Here, ZEB1 is linked to neoplasm.