Fig. 7. skpA^– cells accumulate cyclin E. (A-B) Cyclin E staining in wildtype and skpA^– cells from larvae 3.5 days AED. Stronger cyclin E staining was detected in mitotic cells (M), and in some skpA^– cells (arrowheads). Most cytoplasmic proteins were extracted with these fixation conditions; samples prepared without extraction also had elevated levels of cyclin E in the cytoplasm. Cyclin E did not co-localize with centrosomes in either wildtype or skpA^– cells. Equivalent exposures of cyclin E staining are shown. Bar, 5 µm. (C) Quantification of cyclin E intensity relative to cell cycle stage. DNA content was determined from the total DAPI intensity of each nucleus and correlated with the average cyclin E intensity for the corresponding region. Mitotic cells with a 4C DNA content are shown separately. Significantly higher levels of cyclin E were detected in skpA^– cells with a 3C or more DNA content. Almost no signal was detected in cells from cycE^k05007 larvae. (D) Western analysis of cyclin E levels in skpA⁺ and skpA^– larvae. Cyclin E was detected on a blot identical to the one used for Fig. 6A. Both maternal (77 kDa) and zygotic (67 kDa) cyclin E are detected in extracts from 4-8-hours-old embryos.