Thymidylate synthase as an oncogene?

A surprising finding in the report by Rahman et al. in this issue of Cancer Cell is that forced overexpression of human thymidylate synthase transforms immortalized murine cells into a malignant phenotype. We discuss the possibility that elevated levels of thymidylate synthase noted in some human malignancies may contribute to tumor progression and may also reflect increased levels of its transcriptional activator E2F-1.