our work is funded by the medical research council , eu grant qlk6 - 2000 - 530 , and by the muscular dystrophy campaign .
 gene - expression profiling has yielded important information about simple systems , but complex tissues have not yet been widely profiled . 
 four recent studies of mammalian skeletal muscles have added to the catalogs of their gene expression differences , but have yet to lead to better understanding of the molecular processes underlying their physiological differences . 
Acknowledgements