PD-L1 enhances the CSC-like properties of GC cells via binding CTCF. (A) The expression of CD44, Nanog, Oct4, and N-cadherin in SGC-7901 following siRNA mediated knockdown of CTCF and GCMSC-CM treatment for 24 h were detected by western blot. (B, C) Transwell migration (scale bar, 100 μm) and sphere formation (scale bar, 50 μm) assays were performed in siRNA CTCF-knockdown SGC-7901 following GCMSC-CM treatment for 24 h. (D, E) Quantification of cell migration and sphere numbers. (F) The ALDH activity of siRNA CTCF-knockdown SGC-7901 following GCMSC-CM treatment for 24 h was tested by ALDEFLUOR analyses. Data in D and E represents the mean ± SD of three repeated experiments (n=3). GCMSCs were isolated from three different GC patients. **, P<0.01, ***, P<0.001.