Figure 2. IKKα−/− cells show tumorigenic potential.
(A) IKKα−/− cells grow anchorage-independently in soft agar. Soft agar assays were performed with wild-type MEF, IKKα−/−, IKKβ−/−, IKKγ−/−, and IKKα reconstituted cells. After 14 days, colonies were counted and photographed. CLL230 cells were used as a positive control. (B) IKKα−/− cells induce tumors in athymic nude mice. Six week-old athymic nude mice were injected with 5×106 indicated cells subcutaneously and observed for development of tumor. The figure shows a representative appearance of tumor at twelve days following inoculation of cells (C) Tumor size was measured at 8, 10, and 12 days following injection of the cells and mice not developing tumor were observed up to three weeks. The figure shows average volume (mm3) on indicated days (SD±SEM). (D) Top panel: Paraffin sections from tumor induced by IKKα−/− cells were stained with hematoxylin and eosin. Sections are shown at 100X (a) and 400X (b). Bottom panel: Athymic mice with tumors induced by injection of IKKα−/− cells were injected with BrdU or PBS as described in methods. The frozen sections from these tumors were stained with avidin-conjugated anti-BrdU antibody followed by streptavidin-conjugated hydrogen peroxide. DAB was used as final chromogen.