Inactivation of the ERK pathway did not affect the chromatin condensation, nuclear polarization, or enucleosome formation. (A) Representative cytospin images showing morphology of erythroblasts treated with DMSO or U0126. Blue dotted lines depict the outline of the cells, red dotted lines depict the outline of the nucleus, yellow asterisks indicate the central of the cell or nucleus, and yellow lines indicate the distance between cell and nucleus centroids. Scale bar, 5 μm. (B) Quantitative analyses of the nucleus area from cytospin images. (C) Quantitative analysis of the centroid distance between cell and nucleus. (D) Representative EM images showing morphology of the erythroblasts treated with DMSO or U0126. Green dotted lines depict outline of the nucleus, and red dotted lines depict the euchromatin. Scale bar, 5 μm. (E) Quantitative analysis of the ratio of euchromatin/heterochromatin. (F) Representative immunofluorescence images showing F-actin spot (enucleosome) in erythroblasts treated with DMSO or U0126. White arrows indicate enucleosome. Scale bar, 5 μm. (G) Quantitative analyses of the erythroblasts that contain the enucleosome. A total of 100 cells of each group from 3 independent experiments were used for quantification. (H) Representative western blot showing pAKT, AKT, active Rac1, total Rac1, active RhoA, total RhoA, F-actin, and GPA expression in orthochromatic erythroblasts treated with DMSO or U0126. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) served as the loading control. (I) Quantitative analyses of pAKT, AKT, active Rac1, total Rac1, active RhoA, total RhoA, F-actin, and GPA protein levels from 3 independent experiments. Data are expressed as mean ± standard deviation. n.s., not statistically significant.