In addition, using the Vein-LacZ reporter as a readout of EGF signaling activity [16,24,70,71,72], expression of this reporter was absent in early-stage Zfh-1-positive cyst cells (yellow arrowhead in Fig 5A–5A”), but expression was robust in differentiated cyst cells (yellow arrows in Fig 5A–5A”), suggesting increased EGF signaling activity during normal cyst cell differentiation, as reported previously [22]. This evidence concerns the gene EGF and cyst.