SNAI1 and cancer: This effect of PD-L1 is very likely conducted via regulating the EMT, in the context that the Snail family TFs and the EMT play important roles in stimulating cancer metastasis and progression not only by improving migration and invasiveness but also by conferring tumor cells with stem cell–like traits that enhance the ability of tumor cells to survive in foreign microenvironments, such as in circulation and distant organs (20, 24).