MYC and breast cancer: As the key metabolic enzymes, SHMTs are the direct transcriptional targets of c-Myc (Nikiforov et al., 2002; Nilsson et al., 2012), and SHMT2 can be co-induced by c-Myc and HIF1α to maintain NADPH production and redox balance in neuroblastoma and breast cancer cells (Ye et al., 2014).