ESC-Derived Erythroid Cells 31. Hentze H, Graichen R, Colman A (2007) Cell therapy and the safety of embryonic stem cell-derived grafts. Trends Biotechnol 25: 24–32. 32. Schuldiner M, Itskovitz-Eldor J, Benvenisty N (2003) Selective ablation of human embryonic stem cells expressing a ‘‘suicide’’ gene. Stem cells 21: 257–265. 33. Reubinoff BE, Pera MF, Fong CY, Trounson A, Bongso A (2000) Embryonic stem cell lines from human blastocysts: somatic differentiation in vitro. Nat Biotechnol 18: 399–404. PLoS ONE | www.plosone.org 11 February 2008 | Issue 2 | e1544