Figure 1. A Genome-wide siRNA screen identifies genes involved in epigenetic gene silencing. (A) A GFP reporter-based system for identification of cellular factors involved in epigenetic gene silencing. (B) Outline and summary of the two-step genome-wide siRNA screen. (C) A schematic view of the primary screen (top) and the validation screen (bottom). Bracket over wells indicates placement of alternating positive and negative controls. (D, E) Gene Ontology (GO) analysis of factors identified in the screen: subcellular localization (D) and pathway analysis (E). In Panel E, the colored slices indicate the 67 factors enriched in GO categories, as represented in Figure 2.