Fixed brains and imaginal discs were dissected from 10 third instar larvae, and sonicated chromatin incubated with anti ChIP was performed with 1:100 dilutions of anti-Pho [custom made], anti-Ph (a kind gift from Donna Arndt-Jovin) antibodies and 1:200 dilutions of anti-H3K27me3 (Millipore, 17-622) antibodies.