There was an error published in J. Cell Sci. 121, 939-946.

The reverse primer sequence for RT-PCR in the Materials and Methods is given in the 3′-to-5′ direction, not the 5′-to-3′ direction as stated. The correct sequence of the reverse primer is 5′-TCTTGTGCCATGAGACTCCATCAG-3′.

The authors apologise for this error.