D. Distribution of OCT4 ratios between sister cells before and after BMP4 treatment. Ratios for both sister cells (r and 1/r) are plotted to emphasize central tendency toward r = 1:1. Differently colored curves represent the distribution of ratios at different time points after division. For time points after 5 minutes, the ratio was determined by first calculating a mean OCT4 level for each sister cell among all previous time points and then calculating the resulting ratio between sisters. 