(A-D) Short hairpin RNAs (sh-SHMT1.1 and sh-SHMT1.2) that act against SHMT1 were stably transfected into GC MGC-803 and SGC7901 cells. Silencing of SHMT1, CSC sphere formation, sphere sizes, and CSC-related gene expression were evaluated in Drosha-knockdown MGC-803 and SGC-7901 cells. (A) Images of GCSC spheres (magnification: ×100; scale bar: 100 μm); (B) CSC sphere formation efficiency; (C) CSC sphere sizes. (D) CSC-associated gene expression by western blotting. (E-H). Ectopic SHMT1 was transfected into MGC-803 and SGC-7901 parent cells, and CSC sphere formation, sphere sizes, and CSC-related gene expression were evaluated. (E) Images of GCSC sphere formation in the indicated gastric cancer cells (magnification: ×100; scale bar: 100 μm). (F) CSC sphere formation efficiency. (G) CSC sphere sizes. (H) CSC-associated gene expression in the indicated GCSCs.