Aberrant expression of megakaryocyte-related adhesion proteins and transcription factors in Eklf-null mutant EryP. CD41 (A) and CD31 (Pecam-1, C) protein were up-regulated on EryP/H2B-GFP from Eklf-null E13.5 embryos. (B) Genes encoding the integrin CD41 (Itga2b) and the megakaryocyte transcription factors Fli-1 and Gabpa were strongly up-regulated in EryP sorted from Eklf-null mutant E13.5 embryos, as analyzed using real-time RT-PCR.