SHMT1 and ovarian cancer: Although we found that six genes of the folic acid metabolic pathway were overexpressed in the ovarian cancer samples compared with normal ovary, no other gene knockdown was as effective in inhibiting the growth of ovarian cancer cells as was the knockdown of SHMT1. This finding underpins the importance of functional validation experiments such as ours to distinguish passenger transcriptional changes from driver transcriptional changes in cancer cells.