Using a procedure to stain cells simultaneously for cyclin B1 protein
and DNA, we have examined cyclin B1 expression by flow cytometry in hu
man cells under a variety of perturbing and nonperturbing conditions.
The method described is useful for measuring relative differences in c
yclin B level (immunochemically detectable epitope) as a function of c
ell cycle position on an individual cell basis and thus to examine cel
l cycle-related changes in cyclin B expression without prior cell sync
hronization. We show that in HeLaS3 cells, cyclin B1 accumulates in ce
lls only after they become 4C and have resided in G2 for a short perio
d of time. During colcemid-induced mitotic arrest cyclin BI continues
to accumulate in HeLa S3 cells, and under specific conditions of aphid
icolin-induced unbalanced cell growth induced, cyclin B accumulates to
supranormal levels prior to mitosis. Flow cytometric analysis of cycl
in B expression and DNA content permits detailed examination of the ef
fects of cell cycle perturbations on cyclin B expression under a varie
ty of conditions. (C) 1994 Academic Press, Inc.