Figure 6. Enforced IKKβca expression in primary early passage MEFs produces a transient cell proliferation arrest in association with a G1/S phase cell cycle block during the 1st week of culture.
A: Wild type primary MEFs (passage 4) were stably infected with IKKβca-BIP or BIP empty control vector and maintained under puromycin selection for 5 days post infection. At 7 dpi cells were seeded at low density (∼1000 cells per well) in quadruplicate in 96 well plates and the relative amounts of cell growth were determined by quantifying the increase in DNA (in ng) every 24 hr over a 14 day period (equivalent to 8-21 dpi) as described in Materials and Methods (and also in Fig. 4A legend). All DNA values are expressed as the mean ± s.e.m. Phase contrast microscopy (20X magnification) images of 1° 7 dpi IKKβca-BIP and 1° BIP control MEFs are shown adjacent to the growth curves. B: Vector control and IKKβca 1°MEFs 7 dpi were stained with propidium iodide and submitted to flow cytometry to reveal their cell cycle distribution profiles (as described in Materials and Methods). Data was analyzed with FACSDiva software (Becton-Dickinson). The percentages of cells in G1, S and G2 phases are indicated. Results are representative of several independent experiments.