Endogenous BRCA2 is nuclear. (a) Indirect
immunofluorescence of human breast cancer cells (MCF-7) expressing
full-length BRCA2. Cells were prepared as described in Materials
and Methods, probed with anti-BRCA2A Ab (8) (BRCA2), stained
with DAPI, and then imaged by confocal microscopy. The merged images
are presented on the right. (Bar = 10 μm.) (b)
Biochemical fractionation of MCF-7 cells. MCF-7 cells were separated
into cytoplasmic (Cy) and nuclear (Nu) fractions. WC, whole-cell
extract. Equal numbers of cells were used to prepare the whole-cell and
fractionated lysates. (Top) Anti-BRCA2A Ab was used to
probe for BRCA2. The 250-kDa protein marker band is marked on the
right. To validate the fractionation procedure, separate blots of
protein from the subcellular fractions were probed with antibodies
against the cytoplasmic NF-κB2 p100 precursor protein (38)
(Middle) and the nuclear HIP protein (39)
(Bottom). These proteins fractionated as expected.