Fig. 4. Pho and Psc colocalize to many sites on polytene chromosomes. This figure shows a partial spread of polytene chromosomes from a wild-type larva labelled with Pho (Cy2 labelled, green) and Psc (Cy3 labelled, red) antibodies. The individual Pho and Psc patterns are shown, together with an overlay of the two patterns in the final panel. Of the Pho sites, roughly 65% of them are also sites for Psc. Almost all of the Psc sites overlap with the Pho sites.