Percentage differences of centrosomal F-actin and centrosomal microtubule fluorescence intensities in cells stimulated with BCR-ligand+ beads with respect to cells stimulated with BCR-ligand- beads. The data set is identical to panel (B). Measurements were pooled from 3 independent experiments; IgM (BCR-ligand-): n= 88; IgG (BCR-ligand+): n= 93. Error bars correspond to standard deviations. P values were calculated with one-sample t-test (i.e. comparison to a theoretical mean of "0"). 