Detection of c-Myb, GATA-2, and PU.1 protein after ex vivo culture on FN- versus BSA-coated plates. To determine whether integrin engagement preserves the primitiveness of CD34+ cells, the cells were cultured on FN- versus BSA-coated plates in the presence of IL-3, IL-6, and SCF for 96 hours. A total of 2 × 106 cells were normalized at the end of each culture and subjected to subcellular fractionation and protein analysis for c-Myb and GATA-2, 2 transcription factors reported to be abundant in primitive cells versus PU.1, a transcription factor highly expressed in committed monocytes (A). A quantitative representation of 1 of the 4 bone marrow experiments assessing c-Myb and GATA-2 is shown by normalizing the densitometry value of the transcription factor with that of the corresponding actin densitometry value (B). NA indicates nonadherent; AD, adherent.
