Fig. 6. Location of protein B23 containing Thr199-P during mitosis. Indirect immunofluorescence studies were conducted using the B23 Thr199-P antibody (T199p) to study its location during different phases of mitosis. Cells stained with the DNA-binding dye Hoechst 33342, in different stages of mitosis are indicated by arrows. (A) B23 was phosphorylated at Thr199 at the onset of mitosis as seen by the signal for Thr199-P antibody in early mitotic cells. The surrounding interphase cells showed weak or no signal with this antibody. (B) The signal for Thr199-P antibody was detected during early anaphase but it disappeared as the cell progressed through mid anaphase. In the same panel, one of the cells in metaphase was stained by Thr199-P antibody but no signal was detected in the surrounding interphase cells. (C) With B23 antibody staining, arrowheads and arrows show NDF and PNBs in anaphase and telophase respectively. Corresponding images show that the Thr199-P staining is absent in these cells. Bars, 10 µm.