44. Jordan JJ, Menendez D, Inga A, Noureddine MA, Bell DA, et al. (2008) Noncanonical DNA motifs as transactivation targets by wild type and mutant p53. PLoS Genet 4: e1000104. 45. Espinosa JM, Emerson BM (2001) Transcriptional regulation by p53 through intrinsic DNA/chromatin binding and site-directed cofactor recruitment. Mol Cell 8: 57–69. 46. Espinosa JM, Verdun RE, Emerson BM (2003) p53 functions through stress- and promoter-specific recruitment of transcription initiation components before and after DNA damage. Mol Cell 12: 1015–1027. 47. Berger MF, Bulyk ML (2006) Protein binding microarrays (PBMs) for rapid, high-throughput characterization of the sequence specificities of DNA binding proteins. Methods Mol Biol 338: 245–260. Sequence Variation and p53 DNA Binding 48. Berger MF, Philippakis AA, Qureshi AM, He FS, Estep PW 3rd, et al. (2006) Compact, universal DNA microarrays to comprehensively determine transcrip- tion-factor binding site specificities. Nat Biotechnol 24: 1429–1435. 49. Jegga AG, Inga A, Menendez D, Aronow BJ, Resnick MA (2008) Functional evolution of the p53 regulatory network through its target response elements. Proc Natl Acad Sci U S A 105: 944–949. 50. Menendez D, Inga A, Jordan JJ, Resnick MA (2007) Changing the p53 master regulatory network: ELEMENTary, my dear Mr Watson. Oncogene 26: 2191–2201. 51. Kern SE, Pietenpol JA, Thiagalingam S, Seymour A, Kinzler KW, et al. (1992) Oncogenic forms of p53 inhibit p53-regulated gene expression. Science 256: 827–830. 52. Iannone MA, Consler TG (2006) Effect of microsphere binding site density on the apparent affinity of an interaction partner. Cytometry A 69: 374–383. PLoS Genetics | www.plosgenetics.org 13 May 2009 | Volume 5 | Issue 5 | e1000462