Maria Manuela R. Costa, Samantha Fox, Andy I. Hanna, Catherine Baxter and Enrico Coen Development132, 5093-5101.

Some errors in this article were not corrected before it was sent to press.

In Fig. 2A, 60 bp should have been 24 bp. The correct figure is printed below.

In addition, in the legend to Fig. 10, the first occurrence of `CYC' should have been in italics, as it is referring to the gene and not to the protein.

We apologise to the authors and readers for these mistakes.