The following is in response to a query from Dr. Lucy Cherbas on the identity of the cultured cell line used in Schleich et al., (2014) Nature 512:208 and Schleich and Teleman (2009) PLoS One 4:e6405: Two independent "S2 cell-unspecified" lines were used in Schleich et al., 2014. We independently observed the published phenotypes in both lines. S2 cells of unspecified origin were used in Schleich and Teleman, 2009.