23. Longmore GD (2006) A unique role for Stat5 in recovery from acute anemia. J Clin Invest 116: 626–628. 24. Sathyanarayana P, Dev A, Fang J, Houde E, Bogacheva O, et al. (2008) EPO receptor circuits for primary erythroblast survival. Blood 111: 5390–5399. 25. Bouscary D, Pene F, Claessens YE, Muller O, Chretien S, et al. (2003) Critical role for PI 3-kinase in the control of erythropoietin-induced erythroid progenitor proliferation. Blood 101: 3436–3443. 26. Haseyama Y, Sawada K, Oda A, Koizumi K, Takano H, et al. (1999) Phosphatidylinositol 3-kinase is involved in the protection of primary cultured human erythroid precursor cells from apoptosis. Blood 94: 1568–1577. 27. De Maria R, Testa U, Luchetti L, Zeuner A, Stassi G, et al. (1999) Apoptotic role of Fas/Fas ligand system in the regulation of erythropoiesis. Blood 93: 796–803. 28. Alderson MR, Tough TW, Davis-Smith T, Braddy S, Falk B, et al. (1995) Fas ligand mediates activation-induced cell death in human T lymphocytes. J Exp Med 181: 71–77. 29. Ju ST, Panka DJ, Cui H, Ettinger R, el-Khatib M, et al. (1995) Fas(CD95)/FasL interactions required for programmed cell death after T-cell activation. Nature 373: 444–448. 30. Brunner T, Mogil RJ, LaFace D, Yoo NJ, Mahboubi A, et al. (1995) Cell- autonomous Fas (CD95)/Fas-ligand interaction mediates activation-induced apoptosis in T-cell hybridomas. Nature 373: 441–444. 31. Socolovsky M, Murrell M, Liu Y, Pop R, Porpiglia E, et al. (2007) Negative Autoregulation by FAS Mediates Robust Fetal Erythropoiesis. PLoS Biol 5: e252. 32. Thieffry D, Huerta AM, Perez-Rueda E, Collado-Vides J (1998) From specific gene regulation to genomic networks: a global analysis of transcriptional regulation in Escherichia coli. Bioessays 20: 433–440. 33. Alon U (2007) Network motifs: theory and experimental approaches. Nat Rev Genet 8: 450–461. 34. Savageau MA (1974) Comparison of classical and autogenous systems of regulation in inducible operons. Nature 252: 546–549. 35. Rosenfeld N, Elowitz MB, Alon U (2002) Negative autoregulation speeds the response times of transcription networks. J Mol Biol 323: 785–793. 36. Ramsdell F, Seaman MS, Miller RE, Tough TW, Alderson MR, et al. (1994) gld/gld mice are unable to express a functional ligand for Fas. Eur J Immunol 24: 928–933. 37. Kawai T, Adachi O, Ogawa T, Takeda K, Akira S (1999) Unresponsiveness of MyD88-deficient mice to endotoxin. Immunity 11: 115–122. 38. Nguyen T, Russell J (2001) The regulation of FasL expression during activation- induced cell death (AICD). Immunology 103: 426–434. 39. David Bessman J (1990) Reticulocytes. In: Kenneth Walker H, Dallas Hall W, Willis Hurst J, eds. Clinical Methods: The History, Physical and Laboratory Examinations, 3 ed Boston: Butterworths. pp 735–738. Fas Stabilizes and Accelerates Erythropoiesis 40. Nagata S, Suda T (1995) Fas and Fas ligand: lpr and gld mutations. Immunol Today 16: 39–43. 41. Bader-Meunier B, Rieux-Laucat F, Croisille L, Yvart J, Mielot F, et al. (2000) Dyserythropoiesis associated with a fas-deficient condition in childhood. Br J Haematol 108: 300–304. 42. Mombaerts P, Iacomini J, Johnson RS, Herrup K, Tonegawa S, et al. (1992) RAG-1-deficient mice have no mature B and T lymphocytes. Cell 68: 869–877. 43. Russell ES, Bernstein SE (1966) Blood and Blood Formation. In: Green EL, ed. Biology of the Laboratory Mouse. New York: McGraw-Hill Book Company. pp 351–372. 44. Kline DD, Peng YJ, Manalo DJ, Semenza GL, Prabhakar NR (2002) Defective carotid body function and impaired ventilatory responses to chronic hypoxia in mice partially deficient for hypoxia-inducible factor 1 alpha. Proc Natl Acad Sci U S A 99: 821–826. 45. Schmidt W (2002) Effects of intermittent exposure to high altitude on blood volume and erythropoietic activity. High Alt Med Biol 3: 167–176. 46. Stamatoyannopoulos G, Veith R, Galanello R, Papayannopoulou T (1985) Hb F production in stressed erythropoiesis: observations and kinetic models. Ann N Y Acad Sci 445: 188–197. 47. Seno S, Miyahara M, Asakura H, Ochi O, Matsuoka K, et al. (1964) Macrocytosis Resulting from Early Denucleation of Erythroid Precursors. Blood 24: 582–593. 48. Borsook H, Lingrel JB, Scaro JL, Millette RL (1962) Synthesis of haemoglobin in relation to the maturation of erythroid cells. Nature 196: 347–350. 49. Guihard S, Clay D, Cocault L, Saulnier N, Opolon P, et al. The MAPK ERK1 is a negative regulator of the adult steady-state splenic erythropoiesis. Blood 115: 3686–3694. 50. Schneider E, Moreau G, Arnould A, Vasseur F, Khodabaccus N, et al. (1999) Increased fetal and extramedullary hematopoiesis in Fas-deficient C57BL/6-lpr/ lpr mice. Blood 94: 2613–2621. 51. Socolovsky M (2007) Molecular insights into stress erythropoiesis. Curr Opin Hematol 14: 215–224. 52. Lenox LE, Perry JM, Paulson RF (2005) BMP4 and Madh5 regulate the erythroid response to acute anemia. Blood 105: 2741–2748. 53. McAdams HH, Arkin A (1999) It’s a noisy business! Genetic regulation at the nanomolar scale. Trends Genet 15: 65–69. 54. Stelling J, Sauer U, Szallasi Z, Doyle FJ, 3rd, Doyle J (2004) Robustness of cellular functions. Cell 118: 675–685. 55. Bratsun D, Volfson D, Tsimring LS, Hasty J (2005) Delay-induced stochastic oscillations in gene regulation. Proc Natl Acad Sci U S A 102: 14593–14598. 56. Becskei A, Serrano L (2000) Engineering stability in gene networks by autoregulation. Nature 405: 590–593. 57. Camas FM, Blazquez J, Poyatos JF (2006) Autogenous and nonautogenous control of response in a genetic network. Proc Natl Acad Sci U S A 103: 12718–12723. PLoS ONE | www.plosone.org 14 July 2011 | Volume 6 | Issue 7 | e21192