SMAD2 and neoplasm: As the underlying mechanism of vimentin activation of metastasis and PD-L1 expression, vimentin phosphorylated by PLK1 interacts with p-Smad2/3 for nuclear translocation (Fig. 8b), and nuclear p-Smad2/3 binds to the PD-L1 promoter to trigger PD-L1 expression, enabling immune escape and tumor survival, as analysed by coculture with cytotoxic T cells.