Human erythroblasts express non-muscle myosin IIA and IIB. (A) Western blotting of human PBMCs, CFU-E (day 7 cells, D7) and erythroblasts (D10-D12). D7-D12 indicates days of culture of purified human CD34+ cells to induce erythroid differentiation. At indicated days, the cells were harvested and the protein obtained from 1 × 105 cells was applied to each lane. The relative expression levels of myosin II were normalized with tubulin expression and are the mean ± SD of 3 independent experiments. (B-C) Confocal microscopy of CFU-E (B) and day 12 enucleating mature erythroblasts (C) stained by DAPI, phalloidin and myosin IIA or IIB. NMHC IIA and IIB colocalized with actin (B arrows). In enucleating erythroblasts, NMHC IIB was present on the enucleated reticulocytes in the shape of a small ring colocalized with actin (C arrow).
