SHMT2 and cancer: Antagonizing glycine uptake and its mitochondrial biosynthesis preferentially impaired rapidly proliferating cells; in particular, silencing the mitochondrial SHMT2 gene and deprivation of extracellular glycine slowed down proliferation in HeLa cells and other fast-proliferating cancer cells by prolonging the G1 phase of the cell cycle (Jain, 2012).