Nature 452, 230-233 (13 March 2008) | doi:10.1038/nature06734; Received 18 October 2007; Accepted 19 January 2008 7 o2 O0 u5 b9 a/ y: MThe M2 splice isoform of pyruvate kinase is important for cancer metabolism and tumour growth1 T% ]" K& Q* r8 T Q! I: C: \