In an attempt to understand the molecular mechanisms underlying the interaction between PD-L1 and EMT in the malignant neoplasms studied, the following signaling pathways were analyzed in the present systematic review: ERK/STAT, Rho GTPase, PI3K/AKT, AKT/mTOR, and TGF-β (Table 2). This evidence concerns the gene TGFB1 and cancer.