Comparison of CD34 surface expression versus total CD34 protein expression in CD34⁺ progenitors after culturing on FN- versus BSA-coated plates. After a 48-hour culture, 200 000 cells were stained with anti-CD34–FITC and anti-CD38–PE and analyzed by flow cytometry to assess CD34 cell-surface expression (A). An additional 2 × 10⁶ cells from the same cultures (n = 4) were lysed in protein lysis buffer for CD34 total protein expression by immunoblotting (B). The top half of the blot was immunoblotted for CD34, and the bottom half was immunoblotted for actin as a loading control.