Immunofluorescence staining of checkpoint proteins
in anti-CENP-E–injected HeLa cells. Synchronized cells were injected
with rat anti-CENP-E antibodies 2 h after release from the G1/S
boundary and sampled 10 h later. (a–d) Cells were stained for
hMAD2, hMAD1, hBUB1, and hBUBR1 with the use of appropriate rabbit
antibodies and Texas Red-conjugated anti-rabbit secondary
antibodies. Chromosomes and nuclei were stained with DAPI (left
column). Injected cells exhibited the normal dissociation of checkpoint
proteins from kinetochores of bioriented, aligned
chromosomes. Bar, 10 μm.