their help for culture and transfection of FreeStyle 293-F cells. FUNDING BBSRC (grant number BB/D013917/1) and Wellcome Trust (grant number WT080368MA) awarded to D.J.E.; a Royal Society Joint International Grant (awarded to D.J.E. and J.S.); EURASNET NoE (European Commission FP6) (to J.S.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Funding for open access charge: Wellcome Trust. Conﬂict of interest statement. None declared. REFERENCES 1. Pan,Q., Shai,O., Lee,L.J., Frey,B.J. and Blencowe,B.J. (2008) Deep surveying of alternative splicing complexity in the human transcriptome by high-throughput sequencing. Nat. Genet., 40, 1413–1415. 2. Wang,E.T., Sandberg,R., Luo,S., Khrebtukova,I., Zhang,L., Mayr,C., Kingsmore,S.F., Schroth,G.P. and Burge,C.B. (2008) Alternative isoform regulation in human tissue transcriptomes. Nature, 456, 470–476. 3. Nilsen,T.W. and Graveley,B.R. 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