Forelimbs and hindlimbs are, clearly, quite different, and it has long been
appreciated that their differences are assigned early in development; the
genetic basis of these differences has been more mysterious, however. Recen
t work has now shown that the homeobox gene Pitx1 imparts identity to the d
eveloping hindlimb bud. (C) Elsevier Science Ltd ISSN 0960-9822.