In order to test whether our in vitro identification of mSHMT as one of the key mitochondrial target of arginase in MDA-MB-468 cells has any clinical relevance, we performed quantitative real-time PCR (Figure 4B) and western blot analysis (Figure 4C, left panel) in 26 human breast tumor samples and 12 matched normal fresh tissues (Table S2) using gene specific human primer sets and respective antibodies. Here, SHMT2 is linked to breast neoplasm.