FIG. 4.

CDT leads to accumulation of inactive CDC2. Shown is a Western blot of total HeLa cell proteins isolated from cells treated with either fresh medium (lanes 2, 5, and 8), the vector control extract (lanes 3, 6, and 9), or the recombinant CDT extract (lanes 4, 7, and 10). Lane 1 contains a positive control protein, a CDC2 fusion protein tagged with a hemagglutinin epitope, produced by the baculovirus-Sf9 expression system (gift of Michael Mendenhall, University of Kentucky, Lexington, Ky.). Lanes 2, 3, and 4 contain proteins from HeLa cells harvested 24 h after treatment with medium, vector only extract, and recombinant CDT, respectively. Lanes 5 through 10 represent total proteins from HeLa cells treated for 48 h (lanes 5, 6, and 7) and 72 h (lanes 8, 9, and 10).